The great can protect themselves， but the poor and humble require the arm and hield of the law.
—Andrew Jackson （7th President of the United States）
财产法上的财产可以分为动产和不动产。动产主要指除土地和建筑物以外的有形财产和无形财产。不动产是指土地本身和建筑物，以及树木、土壤、矿藏、植物和其他永久性附着于土地或建筑物之上或之下的物品。对不动产的权利包括对土地与建筑物的权利、空间权利（ Air Right）、地下权利（ Subsurface Right）、对生物（ Vegetation）的权利及对附着物（ Fixtures）的权利6种。
美国财产法起源于英国封建土地法，是调整财产的占有、使用、收益和处分关系的法律规范。财产法以财产为核心，财产法中的财产不仅指人们所拥有的具体的物，还包括人们对该物享有的一系列权利。这些权利包括占有权、使用权、收益权和处分权等一系列财产权利（ Property Rights）。这四种权利可与所有权产生分离，例如，所有权人自愿地有偿或无偿出让这四种权利。不动产是财产法的主要内容。美国不动产法中，不动产和其权益是分开的，法律更加强调不动产权益。取得财产权利的方式有多种。财产所有权的取得主要通过生产（ production）、购买（ purchase）、占有（ possession）、馈赠（ gift）、遗嘱或继承权（ will or inheritance）、财产增值（ accession）、混合和添附（ confusion and accession）、国家征用（ power of eminent domain）、国家警察权力（ police power）等方式。
United States Property Law
Each society has its own conception of the rights of the individual and the rights of the group. A nation s property law usually reflects its basic attitude to individual and group rights. The law of the United States recognizes private owner of property.
The U.S. legal system， like most others， distinguishes between real and personal property. Real property， also called“realty”， is land and the structures built upon it. All other property， such as money， stocks and bonds， jewelry， cars， carloads of lumber， IOUs， bank deposits， is personal property or“personalty”. These correspond roughly to the civil law notions of immovable and movable property. The manner in which the law views these two different types of property varies， especially in regard to the way each is transferred or sold.
We all have a stake in real estate， since we all live somewhere； and we work， study， and travel somewhere， too. Everyone is a renter or an owner， or lives with renters or owners. But for most of us， that as far as the law is concerned the word property means primarily real property； personal property is of minor importance.
Actually， personal property is legally a minor field. There is no single， special field of law devoted to personal property. Personal property is what contract law， commercial law， bankruptcy law and torts are all about. But there are so many special rules about real estate that it makes sense to treat this as a separate field of law.
Property law is still one of the fundamental branches of law， and real estate is a significant branch of law practice. Yet property law is a mere shadow of its former self， legal speaking. In fact， one of the major developments in U.S. system， if you take the long view， is the relative decline of real property law. In medieval England， it would have only been a slight exaggeration to say that land law was the law of the land. When Blackstone published his Commentaries midway through the 18th century， one whole volume was devoted to land law. A modern Blackstone would shrink the topic to a fraction of this bulk—5 or 10 percent， at most， of the total law.
Property law still covers a rich and varied group of subjects. To begin with， it asks： What does it mean to“own”land？ How can I get title to land and how can I dispose of it legally？ There are issues about deeds， joint ownership， and land records and registration； and problems of land finance，including rules about mortgages and foreclosures. There is the law of“nuisance”， which restricts me from using my land in such a way as to hurt my neighbors， pouring smoke or sending bad smells onto his land， for example. These are the law of“easements”and the exotic law of“covenants”（ especially those that“run with the land”） ： these deals with rights a person might have in his neighbor s land—rights to drive a car up his driveway， to walk across his lawn， or to keep him from taking in boarders. These are not rights of ownership； rather they are“servitudes”—restrictions or exceptions to the owner s right， in favor of those others.
The common law was ingenious in carving up rights to land into various complex segments called“estates”. These could be either time segments or space segments. A“life estate”（ my right to live in a certain house， for example， until I die） ， is a time segment； so is a three-year lease of a farm or apartment house. Space segments include air rights （ the right to build on top of certain property） and mineral rights （ the right to dig underneath it） . Nowadays， the condominium is also popular； I can own a slice of some building thirty stories above the ground. The common law was also quite ingenious in devising forms of common or joint ownership， with subtle technical differences between them.
There are also all sorts of“future interests”known to the common law. Suppose I leave my house to my sister for life， and then to any of her children who might be alive when she dies. The children have a future interest； that is， the time they will get the house is postponed to some far-off date. But the future event is certain to happen and thus the future interest can have value and reality now， while my sister is very much alive. The law of future interests developed in a most gnarled and complicated way.
Another important， fairly new， branch of property law is the law of“land use controls”. It deals with the limit imposed on what people can do with their property. This was an issue in the law of nuisance， but modern controls go far beyond this. Zoning is a familiar type of land use restriction. Zoning ordinances date from about the time of the FirstWorld War； they are now almost universal in cities and villages. Zoning ordinances divide towns into zones designated for different uses. If my neighborhood is“zoned”residential， I cannot build a factory or run a restaurant on my property. If the zone is restricted to single-family dwellings， I cannot even run a rooming house or rent out apartments.