Property is where law and economics meet, but it's not a simple concept. Property is not an object or a relation between people and objects, but a set of rights, relations among people over who is to control each of the many uses to which objects can be put. Different people may control different uses of an object, that is, have different property rights over its various uses, at the same time, or control the same use of the object at different times. When new uses create disputes, the law must define new property rights and allocate them initially to resolve the dispute – someone must be deemed to have won the dispute and be given initial ownership of the new rights. But once the former disputants are allowed to trade these rights among themselves, surprising results follow.