An easement is the right to do something or the right to prevent something over the real property of another. At common law, an easement came to be treated as a property right in itself and is still treated as a kind of property by most jurisdictions. In some jurisdictions, another term for easement is "equitable servitude".
The right is often described as the right to use the land of another for a special purpose. Unlike a lease, an easement does not give the holder a right of "possession" of the property, only a right of use. It is distinguished from a license that only gives one a personal privilege to do something on the land of another. An example of a license is the right to park a car in a parking lot with the consent of the parking lot owner. Licenses in general can be terminated by the property owner much more easily than easements. This is similar to a but not the same as a wayleave. Easements also differ from licenses in that they are attached to the land, not to a person. This means that a property that enjoys an easement over another will continue to enjoy the easement even if the property gets transferred to a different owner.
Easement concepts differ substantially from country to country, and in the U.S. from state to state. Historically, it was limited to the right-of-way and rights over flowing waters, although this is no longer true. Traditionally, it was a right that could only attach to an adjacent land and was for the benefit of all, not a specific person; this is also no longer true in many jurisdictions.