Classifications of Property and the Doctrine of Fixtures

Blackstone opens his treatment of things with a taxonomy that Anglo-American law still uses. Chapter 3 established property as a set of legal relations. This chapter identifies the objects to which those relations attach and explains why the law treats them differently. Every classification examined here — real and personal, tangible and intangible, corporeal and incorporeal, public and private, fixture and chattel — carries doctrinal consequences that reappear throughout this treatise in the law of estates, conveyancing, mortgages, recording, taxation, probate, secured transactions, and landlord-tenant relations.

1. Classification determines consequence. The characterization of an interest as real or personal, tangible or intangible, corporeal or incorporeal, public or private, or fixture or chattel selects the substantive law that governs its creation, transfer, taxation, and enforcement.
2. Real property is land and its legal incidents. Land includes the surface, the subsurface, appurtenant airspace, water rights recognized by state law, mineral interests, and improvements that have become part of the realty.
3. Personal property is everything else. Personal property comprises chattels, choses in possession, and choses in action, whether tangible or intangible.
4. Corporeal and incorporeal describe the mode of interest. Corporeal interests are possessory in a physical thing; incorporeal interests are legal rights exercisable with respect to a thing without possession of it.
5. Public and private describe the holder. Public property is held by a sovereign for public purposes; private property is held by natural or juridical persons; mixed and quasi-public interests exist across the spectrum.
6. Fixtures mark the boundary. A chattel affixed to realty in the manner and with the intention required by law becomes part of the realty for most legal purposes, though the Uniform Commercial Code preserves a discrete regime for security interests in fixtures.
7. The annexation, adaptation, and intention test governs. American courts determine fixture status by examining the mode of attachment, the adaptation of the chattel to the use of the realty, and the objectively manifested intention of the annexor.
8. Trade, agricultural, and domestic fixtures are removable at common law. Historic exceptions permit tenants to remove chattels annexed for trade, agriculture, or domestic use, subject to restoration and timely removal.
9. UCC Article 9 governs security interests in fixtures. Section 9-334 supplies priority rules between fixture secured parties and interests in real property; fixture filings under § 9-501 perfect security interests in goods that are or will become fixtures.
10. Classification is doctrinal, not intuitive. Classifications are determined by legal rules, not by the physical characteristics of the resource or the layperson's expectations; misclassification is a leading source of error in conveyancing, secured transactions, probate, and litigation.

• State the historical origin of the real-personal, corporeal-incorporeal, and tangible-intangible divisions.
• Enumerate the components of real property and identify appurtenances, airspace, subsurface, water, and mineral interests as legal incidents of land.
• Distinguish tangible from intangible personal property and choses in possession from choses in action.
• Apply the annexation, adaptation, and intention test to determine whether a chattel has become a fixture.
• Identify the common-law exceptions for trade, agricultural, and domestic fixtures and the conditions on removal.
• Apply UCC §§ 9-102, 9-334, and 9-501 to priority disputes between fixture secured parties and interests in real property.
• Explain how classifications operate in sales, mortgages, foreclosures, probate, taxation, insurance, secured transactions, and landlord-tenant disputes.
• Compare the common-law fragmentation of property with the civilian tradition of unitary dominium and movable-immovable classification.
• Diagnose and correct the recurring lay misconceptions about fixtures, trade fixtures, improvements, and movable property.
• Deploy the vocabulary of classification in the analysis of the estates, conveyances, mortgages, recording, and priority disputes treated in later chapters.

• 2 William Blackstone, Commentaries on the Laws of England *16–*43 (1766).
• Roger A. Cunningham, William B. Stoebuck & Dale A. Whitman, The Law of Property §§ 1.1–1.5, 2.16–2.22 (3d ed. 2000).
• John E. Cribbet, Corwin W. Johnson, Roger W. Findley & Ernest E. Smith, Property: Cases and Materials 1–35, 245–283 (10th ed. 2015).
• Jesse Dukeminier, James E. Krier, Gregory S. Alexander, Michael H. Schill & Lior Jacob Strahilevitz, Property 1–19, 663–698 (9th ed. 2018).
• Herbert T. Tiffany & Basil Jones, The Law of Real Property §§ 601–626 (3d ed. rev. 2020).
• Ray Andrews Brown, The Law of Personal Property §§ 1.1–3.7, 16.1–16.14 (3d ed. 1975).
• James Barr Ames, The Nature of Ownership, in Lectures on Legal History 192 (1913).
• James J. White, Robert S. Summers & Robert A. Hillman, Uniform Commercial Code §§ 30-1 to 30-13 (6th ed. 2010).
• Grant S. Nelson, Dale A. Whitman, Ann M. Burkhart & R. Wilson Freyermuth, Real Estate Finance Law §§ 9.1–9.6 (6th ed. 2015).
• Restatement (First) of Property, Introductory Note (1936).

Property law does not treat all resources alike. Land is governed by one body of doctrine, chattels by another, and intangibles by still a third. The distinctions are not accidents of history but the products of deliberate legal choice. They allocate resources between courts, between remedies, between statutes of frauds and statutes of limitations, and between competing claimants at every stage of the propertied life cycle.

Chapter 3 established that property is a set of legal relations. This chapter identifies the objects to which those relations attach and explains why the law treats each category differently. Classification is the doctrinal bridge between the abstract concept of property and the concrete rules that govern its acquisition, use, transfer, taxation, and defense.

The classification of a resource determines, at a minimum, which body of substantive law applies, which recording or filing system perfects an interest in it, which court has jurisdiction over disputes concerning it, which statute of frauds governs its transfer, which statute of limitations bars claims for its recovery, which remedies are available for its dispossession, which tax regime measures its value, and which succession rules distribute it at death. A single misclassification can defeat a security interest, void a conveyance, misfile a mortgage, or shift a substantial tax liability.

The real-personal divide is the oldest classification in Anglo-American law. Its origin lies in the forms of action. A claimant dispossessed of land sued in a real action for the res itself; a claimant deprived of a chattel sued in a personal action for damages. Because the plaintiff in a real action recovered the thing and the plaintiff in a personal action recovered only compensation, the substantive categories tracked the procedural remedies. Land was res; chattels were personalty. Chapter 2 traced the development of these forms; this chapter treats their doctrinal residue.

The corporeal-incorporeal division comes to us through Roman and canonical sources refracted through Bracton and Blackstone. Corporeal hereditaments were tangible things capable of manual seisin — land, houses, standing timber. Incorporeal hereditaments were intangible legal interests exercisable with respect to the corporeal — advowsons, franchises, rents, easements, profits. Blackstone catalogued the incorporeal hereditaments as ten in number; modern law preserves the categorical distinction but rearranges the contents.

The tangible-intangible personal-property distinction developed later, in response to the rise of commercial paper, negotiable instruments, choses in action, and, in our own era, digital and dematerialized assets. The distinction is now doctrinally central to the law of secured transactions, taxation, and conflicts of laws.

The classification of a resource determines, at a minimum, the governing body of substantive law. Real property is governed by the law of estates, conveyances, servitudes, mortgages, recording, and land use. Personal property is governed by the law of sales, gifts, bailments, and secured transactions. Choses in action are governed by the law of assignment, negotiation, and set-off. The classification also determines the applicable statute of frauds — the seventh section of the Statute of Frauds of 1677 requires a writing for the sale of any interest in land, while the seventeenth section required a writing for the sale of goods above a threshold value (now codified in UCC § 2-201). The classification determines the statute of limitations, the appropriate remedy, the proper court, the recording or filing system, and the tax regime. It also determines the succession rules: real property historically descended to the heir under the canons of descent, while personal property was distributed by the ordinary under the statutes of distribution. These divergent succession rules were largely merged in American law by the twentieth century, but their traces remain in probate, escheat, and choice-of-law doctrine.

Real property is land and the legal interests that attach to land. Chapter 1 established the general definition; this Part identifies the specific components. Real property comprises the surface, the subsurface, appurtenant airspace, water rights recognized by state law, mineral interests, improvements that have become part of the realty, and the incorporeal hereditaments that run with the land.

Land in the legal sense is not merely the two-dimensional surface. The classical maxim cuius est solum, eius est usque ad coelum et ad inferos — whoever owns the soil owns to the heavens and to the depths — captures the common-law conception. Improvements are structures and other permanent additions that have merged with the land. Appurtenances are rights, easements, and privileges that pass with the land because they are incident to its enjoyment. A recorded conveyance of land presumptively conveys the improvements and appurtenances, whether or not they are separately identified.

The Restatement (First) of Property § 5 defines land as a portion of the earth's surface together with all things beneath and above it. The Restatement recognizes that the ownership of land ordinarily extends downward to the center of the earth and upward to the sky, subject to statutory and constitutional limitations. Modern doctrine and statute have qualified the maxim substantially, especially with respect to airspace and mineral interests, but the underlying principle remains: land is a three-dimensional legal object, and the vertical dimensions are as much a part of the realty as the surface.

The ad coelum maxim once described an unlimited vertical column of ownership. Modern aviation and mineral extraction have compelled its qualification. In United States v. Causby, 328 U.S. 256 (1946), the Supreme Court held that low-altitude military overflights constituted a compensable taking of the landowner's airspace, but observed that the ancient maxim has no place in the modern world and that the public has a right of free transit through the navigable airspace. The current regime allocates the immediately superjacent airspace to the surface owner and the navigable airspace above it to the public.

The subsurface remains largely with the surface owner, subject to a distinct body of doctrine governing mineral interests. A mineral estate may be severed from the surface by conveyance or reservation, creating separate estates in the surface and in the minerals. The severance produces the implied easement of reasonable use of the surface for extraction of the severed minerals — a doctrine developed in the oil, gas, and mining states and now embedded in state property law.

Water is not owned in the common-law sense; it is subject to usufructuary rights. American jurisdictions divide broadly into riparian systems, prevailing in the eastern states, and prior-appropriation systems, prevailing in most of the western states. Under the riparian doctrine, the owner of land bordering a watercourse has a natural right to the reasonable use of the water in common with other riparians. Under the prior-appropriation doctrine, the water right belongs to the first person to divert the water and apply it to a beneficial use, without regard to the ownership of the abutting land. Groundwater is governed by separate rules — absolute ownership, reasonable use, correlative rights, or prior appropriation — varying by jurisdiction. The full doctrinal treatment appears in the water-rights chapters of this treatise; the point here is that water rights are real property interests, notwithstanding the peculiarities of their doctrinal framework.

Personal property comprises every propertied interest that is not real property. The category is definitionally residual, but its internal structure is highly articulated. Personal property is subdivided into tangible and intangible property, and into choses in possession and choses in action.

Tangible personal property — chattels or goods — consists of movable physical objects that have an existence apart from land. UCC § 9-102(a)(44) defines goods as all things that are movable when a security interest attaches. Tangible personal property is governed principally by Articles 2, 2A, and 9 of the Uniform Commercial Code, by the common law of bailment, and by the traditional actions of trover, conversion, replevin, and detinue. Passage of title to tangible personal property ordinarily requires delivery, whether actual, constructive, or symbolic — a point examined in detail in Chapter 5.

Intangible personal property consists of legally protected interests that have no independent physical existence. It includes accounts receivable, bank deposit accounts, contract rights, negotiable and non-negotiable instruments, investment securities, general intangibles, and intellectual property. The Uniform Commercial Code provides an elaborate classificatory apparatus for intangible personal property in the context of secured transactions: accounts (§ 9-102(a)(2)), chattel paper (§ 9-102(a)(11)), deposit accounts (§ 9-102(a)(29)), instruments (§ 9-102(a)(47)), investment property (§ 9-102(a)(49)), and general intangibles (§ 9-102(a)(42)).

Intellectual property — patents, copyrights, trademarks, and trade secrets — is a distinct species of intangible personal property governed by federal statute, state law, and international convention. This treatise treats intellectual property only in the introductory sense necessary to situate it within the general theory of property. The specialist doctrine is left to the field's own treatises.

The common law distinguishes between choses in possession — tangible chattels subject to physical possession — and choses in action — rights of action against another person, enforceable only by suit. The archetypal chose in action is a debt: the creditor has no res in hand, only a right to compel payment. Negotiable instruments, insurance policies, unliquidated tort claims, and contract rights are all choses in action. The distinction matters for assignment, negotiation, priority, and the applicable statute of limitations. A chose in action is transferable only by assignment (or, if negotiable, by negotiation); a chose in possession is transferable by delivery.

The corporeal-incorporeal distinction cuts across the real-personal division. A corporeal interest is possessory in a physical thing: fee simple absolute in land, ownership of a chattel, possession of a tangible instrument. An incorporeal interest is a legal right exercisable with respect to a thing without possession of it. The distinction remains central to the law of servitudes, easements, profits, licenses, franchises, and intellectual interests.

An easement is a non-possessory right to use the land of another for a specific purpose. Easements are property interests and are protected by the same remedies that protect possessory interests, adjusted for their non-possessory character. A profit à prendre is a right to enter the land of another and remove some part of the soil or a product of the soil — timber, minerals, wild game — and is treated as a species of easement. A license is a mere permission to enter, revocable at will unless coupled with an interest or executed. The full treatment appears in the servitudes chapters of Volume II; the point here is that easements and profits are incorporeal interests in land, while licenses are ordinarily not property interests at all.

The Restatement (Third) of Property: Servitudes § 1.1 collapses the historical categories of easement, real covenant, and equitable servitude into a unified law of servitudes, but retains the corporeal-incorporeal distinction for purposes of creation, transfer, and termination. American courts continue to speak in the older vocabulary, and this treatise preserves the traditional terminology alongside the Restatement's synthesis.

A franchise is a special privilege conferred by government, historically including corporate charters, ferry and bridge franchises, and utility franchises. Franchises are incorporeal interests, transferable and inheritable, but subject to the terms of the grant. Intellectual interests — patents, copyrights, trademarks, trade secrets, and rights of publicity — are the modern analogues, though most are now governed by federal statute rather than by state property law. The classical incorporeal hereditaments of Blackstone have largely given way to statutory intellectual property regimes, but the classificatory framework remains useful for locating these interests within the general theory of property.

The distinction between public and private property is defined by the identity of the holder. Public property is held by the sovereign — federal, state, tribal, or municipal — for governmental or public purposes. Private property is held by natural or juridical persons. Between these poles lie categories of mixed and quasi-public ownership: property held by public corporations, by charitable trusts, by cooperatives, by common-interest communities, and by regulated utilities and other franchised enterprises.

Government property is held in two doctrinally distinct capacities. Property held in a proprietary capacity is treated substantially like private property; the government may hold, use, transfer, and litigate over it under ordinary property rules, subject to statutory constraints. Property held in a sovereign or governmental capacity — public streets, parks, waterways, and the like — is subject to the public trust doctrine and to the rules governing dedications, vacations, and abandonments. The public trust doctrine, of Roman origin, holds that certain resources — navigable waters and the lands beneath them — are held in trust by the state for the benefit of the public and cannot be alienated to purely private uses without express legislative authority. The doctrine was recognized in Illinois Central Railroad Co. v. Illinois, 146 U.S. 387 (1892), and remains a live constraint on state alienation of trust resources.

Private property is held by natural or juridical persons under the ordinary rules of property, contract, and inheritance, subject to the constitutional and general-law envelope described in Chapter 3. The category is not homogeneous: it includes fee simple absolutes, limited estates, concurrent estates, common-interest developments, cooperative apartments, condominiums, and trust interests, each of which is treated in later chapters of this treatise. The line between public and private is often permeable — through eminent domain, dedication, escheat, condemnation, and abandonment — and much of American property law concerns transactions across that line.

The doctrine of fixtures governs the transformation of chattels into realty and, in certain circumstances, the reverse. It is the boundary doctrine of Anglo-American property law: it decides whether a heating system, a barn, an oven, a wind turbine, or a manufacturing line is part of the land — and therefore passes with the land on conveyance, is subject to the mortgage on the land, is taxed as real property, and descends as land — or remains a chattel with an independent legal life.

The doctrine matters at every stage of the propertied life cycle. It matters at closing, because the sale of land ordinarily conveys the fixtures and does not convey the chattels. It matters in mortgage foreclosure, because the mortgage on the land ordinarily reaches the fixtures. It matters in probate, because real property descends under one set of rules and personal property under another. It matters in tax assessment, because real and personal property are taxed under different regimes. It matters in secured lending, because UCC Article 9 recognizes fixtures as a distinct collateral category with its own priority rules. And it matters in landlord-tenant law, because the common-law doctrines of trade, agricultural, and domestic fixtures determine what the tenant may remove at the end of the term.

A fixture is a chattel that has become so annexed to real property, and so adapted to its use, that the law treats it as part of the realty. UCC § 9-102(a)(41) defines fixtures for Article 9 purposes as goods that have become so related to particular real property that an interest in them arises under real property law. The common-law definition is broader in principle but is applied through the same essential test: annexation, adaptation, and intention.

The classical formulation, associated with Teaff v. Hewitt, 1 Ohio St. 511 (1853), and adopted in various forms across American jurisdictions, comprises three elements. First, annexation — the mode and degree of physical attachment to the realty, whether by embedding, bolting, cementing, or by mere placement in a manner that indicates permanent connection. Second, adaptation — the appropriateness of the chattel to the use or purpose of the realty, so that the two together form a functional whole. Third, intention — the objectively manifested intention of the annexing party to make the chattel a permanent accession to the realty.

Of the three elements, intention has become the controlling factor in most modern American decisions. Intention is not the subjective state of mind of the annexor but is inferred from the annexor's status and interest in the realty, the nature and purpose of the annexation, the relation of the parties, and the customary use of the chattel. See Strain v. Green, 25 Wash. 2d 692, 172 P.2d 216 (1946); George L. A. Brown Co. v. Pontiac Cedar Lumber Co., 293 Mich. 264, 291 N.W. 823 (1940). Annexation and adaptation remain probative of intention, but the controlling question is what the annexor's conduct objectively signifies about permanence.

The common law developed exceptions to the general rule of accession for tenants who annex chattels for specific purposes. Trade fixtures — chattels annexed by a tenant to conduct trade or business — are removable by the tenant during the term or within a reasonable time thereafter, provided that removal does not cause substantial injury to the freehold. The rule originated in commercial policy: without an exception, no tenant would install trade equipment on leased premises, and business enterprise would suffer.

Agricultural fixtures — buildings, machinery, and improvements annexed by an agricultural tenant — were historically not removable under the strict common-law rule, but American courts and statutes have generally extended the trade-fixture principle to agricultural annexations. Domestic fixtures — chattels annexed by a tenant for domestic convenience or ornament — are likewise removable under most modern authorities. The three exceptions rest on the same underlying principle: annexation for the tenant's business, agricultural, or domestic purposes does not manifest an intention to enrich the landlord.

The right to remove a tenant fixture is conditional. The tenant must remove during the term or within a reasonable time after termination; delay converts the fixture into the landlord's property by accession. Removal must not cause substantial injury to the freehold, and the tenant is ordinarily obligated to restore the premises to their prior condition or to compensate for injury caused by removal. Fixtures that cannot be removed without destroying the chattel or the realty are, in effect, not removable. The parties' lease often modifies the common-law rules, and the modern lease routinely allocates fixture rights by express provision. Where the lease is silent, the common-law defaults apply.

A conveyance of real property presumptively conveys all fixtures unless the deed reserves them expressly. Purchasers are entitled to receive the land as they inspected it, with the fixtures in place. A mortgage of real property presumptively encumbers all fixtures, present and after-acquired, unless the mortgage instrument or applicable law provides otherwise. The Restatement (Third) of Property: Mortgages § 1.1 recognizes the mortgage as an interest in real property and applies the general fixture doctrine to determine the scope of the encumbered estate. In foreclosure, the mortgagee reaches the fixtures unless they have been effectively severed or have been made subject to a prior perfected fixture security interest under UCC § 9-334.

The Uniform Commercial Code recognizes fixtures as a distinct collateral category and provides a discrete regime for security interests in fixtures. The regime coexists with, but does not displace, the state law of fixtures for other purposes. A security interest in fixtures is created and attached under the general rules of Article 9; the specialized rules govern perfection and priority against competing interests in the real property.

UCC § 9-501(a)(1)(B) provides that a fixture filing — a financing statement filed in the office designated for the recording of mortgages on the related real property, containing the additional information required by § 9-502(b) — perfects a security interest in goods that are or are to become fixtures. The fixture filing is the analogue of the real-property mortgage, filed in the same office and indexed under the real-property records, so that a searcher of title can discover the security interest. A financing statement filed in the ordinary UCC filing office also perfects a security interest in fixtures, but does not enjoy the priority accorded to a fixture filing under § 9-334.

Section 9-334 supplies the priority rules for security interests in fixtures against conflicting interests in the real property. The general rule is that a security interest in fixtures may be subordinate or superior to a conflicting interest of an encumbrancer or owner of the real property depending on the timing and manner of perfection. Several key rules structure the analysis. First, a purchase-money security interest in fixtures perfected by fixture filing before the goods become fixtures, or within twenty days thereafter, has priority over a conflicting interest of an encumbrancer or owner of the real property if the debtor has an interest of record in the real property or is in possession. § 9-334(d). Second, a security interest in fixtures perfected by fixture filing has priority over the conflicting interest of an encumbrancer or owner if the security interest is perfected by fixture filing before the interest of the encumbrancer or owner is of record, and the security interest has priority over any conflicting interest of a predecessor in title. § 9-334(e)(1). Third, a security interest in readily removable factory or office machines, or readily removable equipment not primarily used in the operation of the real property, may enjoy priority even without a fixture filing under certain circumstances. § 9-334(e)(2). The full architecture of § 9-334 is intricate; the point here is that Article 9 creates a specialized priority regime for fixture collateral that must be navigated alongside, not in place of, the state law of real property and mortgages.

The classifications examined in this chapter are creatures of the Anglo-American tradition. The civil-law systems descended from Roman law employ a different classificatory grammar. Movables and immovables — the Roman res mobiles and res immobiles — replace the common-law real and personal categories. Corporeal and incorporeal things — res corporales and res incorporales — cross both traditions but carry different doctrinal consequences. The unitary conception of ownership (dominium) that governs the civil law refuses the common-law fragmentation into estates and interests. The fixture doctrine appears in civilian codes as the doctrine of accession — accessio — with rules governing the union of movable and immovable property that resemble the common-law tests without adopting the tenant-fixture exceptions.

Modern statutory approaches within American law increasingly displace common-law fixture doctrine with specific statutory rules for manufactured homes, wind turbines, solar installations, and other resources that do not fit comfortably within the historical categories. State legislatures have enacted specialized regimes governing the taxation, financing, and titling of these hybrid assets, and the general common-law doctrine now operates against the background of an expanding statutory overlay. Chapter 4 identifies the classical categories; later chapters treat the modern statutory adjustments in their proper doctrinal context.

The classifications examined in this chapter produce concrete consequences in every setting where property is transferred, financed, taxed, insured, or litigated. The following are the principal doctrinal effects that recur throughout this treatise.

• Sales. A sale of land ordinarily conveys the improvements and fixtures; a sale of goods does not convey the realty. UCC § 2-107 and state fixture law govern intermediate cases.
• Mortgages and Foreclosures. A real-property mortgage reaches fixtures unless the fixture is subject to a prior perfected security interest under UCC § 9-334. The mortgagee's remedy is foreclosure of the land, including its fixtures; the fixture secured party's remedy is enforcement of the security interest under Article 9.
• Probate. Real property historically descended to the heir and personal property was distributed by the ordinary; modern statutes have largely merged the succession rules, but the classification still governs the applicable form of administration, homestead protection, spousal election, and choice of law.
• Taxation. Real and personal property are taxed under separate assessment regimes in every American jurisdiction. Fixture classification determines whether a resource is assessed as part of the land or as separate personal property.
• Insurance. Real-property and personal-property policies cover different classes of loss; the fixture status of a resource determines which policy responds and whether coverage extends at all.
• Secured Transactions. The classification determines whether the interest is perfected by UCC filing, by fixture filing, or by real-property mortgage — and, correspondingly, which searcher can discover it.
• Landlord-Tenant Disputes. The trade-, agricultural-, and domestic-fixture doctrines determine what the tenant may remove at the end of the term; disputes over fixtures at lease termination are a staple of commercial and residential real-estate litigation.
• Recording and Title. Real-property interests are recorded in the real-property records; personal-property interests are filed in the UCC filing office; fixture interests are filed in the real-property records under UCC § 9-501 in order to be discoverable by title searchers.

Fixture doctrine and property classification are among the most misunderstood areas of everyday property law. The following corrections address recurring lay and even professional misconceptions.

1. “If I bolted it in, I can take it out.” Mode of attachment is only one of the three elements of the fixture test. Adaptation and objectively manifested intention frequently override the annexor's later desire to remove.
2. “Trade fixtures are always removable.” Trade fixtures are removable only during the tenancy or a reasonable time thereafter, only without substantial injury to the freehold, and only subject to restoration or compensation.
3. “Improvements are always real property.” Whether an improvement is real or personal property depends on the fixture test, not on the physical fact of construction. A tenant's trade fixture is an improvement in the physical sense but remains personal property in the legal sense.
4. “Movable property is personal property.” Movability is not the legal test. Growing crops are movable but are treated as real property in some contexts and personal property in others under UCC § 2-107; standing timber and unmined minerals are immovable but may be sold as goods.
5. “The deed will list what conveys.” A deed of land ordinarily conveys the fixtures and appurtenances without specific enumeration. Parties who wish to reserve fixtures must do so expressly; parties who wish to sever chattels must do so before closing.
6. “If it’s attached, the bank owns it.” A real-property mortgage does not automatically defeat a prior perfected fixture security interest. UCC § 9-334 protects the fixture secured party who complies with the fixture-filing regime.
7. “Personal property means physical stuff.” Personal property comprehends every propertied interest that is not real property, including choses in action, accounts receivable, negotiable instruments, investment securities, and intellectual property.
8. “Ownership of the surface is ownership of everything above and below.” The ad coelum maxim has been substantially qualified by aviation law, mineral severance, and the public trust doctrine. Modern doctrine allocates the vertical dimensions among the landowner, the public, and severed mineral estate holders.

Chapter 3 established that property is a set of legal relations. This chapter has classified the objects to which those relations attach. Anglo-American law divides property into real and personal, corporeal and incorporeal, tangible and intangible, public and private. The classifications are not merely descriptive: they select the substantive law that governs creation, transfer, taxation, and enforcement. Land includes the surface, the subsurface, appurtenant airspace, water rights, mineral interests, improvements, and incorporeal hereditaments. Personal property comprises chattels, choses in possession, and choses in action, whether tangible or intangible. Incorporeal interests — easements, profits, franchises, and intellectual interests — are legal rights exercisable with respect to a thing without possession of it. Public and private property are distinguished by the identity of the holder, with a large intermediate zone of mixed and quasi-public interests.

The doctrine of fixtures marks the boundary between real and personal property. A chattel becomes a fixture when it is annexed to real property, adapted to its use, and annexed with the objectively manifested intention that it become part of the realty. The common law developed important exceptions for trade, agricultural, and domestic fixtures, permitting tenants to remove chattels annexed for those purposes within the term and without substantial injury to the freehold. The Uniform Commercial Code, in § 9-102(a)(41) and § 9-334, creates a specialized regime for security interests in fixtures, perfected by fixture filing in the real-property records under § 9-501, and prioritized against conflicting interests in the realty under the intricate rules of § 9-334.

The classifications examined here recur throughout this treatise. Chapter 5 addresses acquisition of property by possession and discovery — the first mode of acquiring interests in both real and personal property. Later chapters treat the estates in land, concurrent estates, servitudes, land use, and finance, each of which presupposes the classifications this chapter has established. The reader now possesses the vocabulary necessary to locate any propertied interest within the general architecture of Anglo-American property law.

• 2 William Blackstone, Commentaries on the Laws of England *16–*43 (1766) (classical taxonomy of things).
• Restatement (First) of Property §§ 1–10, 5, 7 (1936) (definitions of land and interests).
• Restatement (Third) of Property: Servitudes § 1.1 (2000) (unified law of servitudes).
• Restatement (Third) of Property: Mortgages § 1.1 (1997) (mortgage as interest in real property).
• Uniform Commercial Code §§ 2-107, 9-102, 9-334, 9-501, 9-502 (2022 rev.).
• Roger A. Cunningham, William B. Stoebuck & Dale A. Whitman, The Law of Property §§ 1.1–1.5, 2.16–2.22 (3d ed. 2000).
• Ray Andrews Brown, The Law of Personal Property §§ 16.1–16.14 (3d ed. 1975).
• James J. White, Robert S. Summers & Robert A. Hillman, Uniform Commercial Code §§ 30-1 to 30-13 (6th ed. 2010) (fixtures under Article 9).
• Grant S. Nelson et al., Real Estate Finance Law §§ 9.1–9.6 (6th ed. 2015) (fixtures in mortgage law).
• Teaff v. Hewitt, 1 Ohio St. 511 (1853) (classical annexation-adaptation-intention test).
• United States v. Causby, 328 U.S. 256 (1946) (airspace and the ad coelum maxim).
• Illinois Central Railroad Co. v. Illinois, 146 U.S. 387 (1892) (public trust doctrine).