Intellectually, it's understood by almost no one. To most people, the idea of ownership brings to mind a relationship between people and objects. We speak of owning our computers, cars, and homes. Actually, the legal concept of ownership is about relationships between people with respect to those objects. Everything that can be owned has a bundle of sticks associated with it.
Ownership is a matter of how the sticks are distributed.
Joe gets the right to possess the home, to make limited changes to the home, to use the home, to invite others into the home, and so on. But Joe doesn't have the right to dispose of the home without first consulting the mortgage company. Under most mortgage agreements, Joe is also limited in his ability to make structural modifications to the home. Joe has and which rights the mortgages company has. When it comes to the ownership of intellectual property, however, the picture is often not so clear.