The term, “intellectual property”, represents a metaphorical extension of a straightforward concept, the ownership of physical goods. Ownership is now extended from entities that can be described with spatial coordinates to the much more impalpable area of knowledge, generally knowledge how to do something useful, to produce something valued in the market. The usual picture of “property” is that it is in scarce supply and that it can be alienated, that is, if ownership is transferred from one individual to another, the former doesn’t have it in any sense while the latter does. Among other implications of these facts is that markets are a suitable way of transferring ownership. Given a legal framework which enforces sales contracts, the ownership is clearcut and practically self-enforcing.