Another party's legal right to enter your property.
An easement gives another party the standing right to enter your property, and in some cases to perform work on your property, without having to ask for permission each time.
An easement is a type of encumbrance.
An easement must state a specific purpose, and must be registered on the title.
An easement "runs with the land", which means buyers are obligated to accept it if they buy the property.
The most common example of an easement is for a hydro worker to access an electrical box on your property.
Another example is a joint driveway, which in fact is owned by only one of the parties, with an easement given to the neighbor.