An easement is an interest in land that is owned by another person and gives the easement holder or easement owner the right to use or control the other person’s land in some limited way—such as the right to drive across another person’s private property to access a public highway or other public road (an ingress-and-egress easement).

There are many different types of easements, depending on the nature of the use of the land—such light-and-air easements; mineral easements; timber easements; noise easements; and railroad easements—and how the easement was acquired—an express easement; an implied easement; a prescriptive easement; an easement by necessity; or an easement by estoppel, for example.

There are also negative easements that prohibit the owner of a property (the servient-estate) from doing something, such as building a home or structure that blocks the view or sunlight for an easement holder—often an adjoining property owner (the dominant estate).

Public utility companies (gas, electricity, telephone, water, sewer, cable, etc.) often have easements to place utility transmission, distribution, or power lines on private property and access them for installation, repair, and maintenance.

Laws regarding easements vary from state to state and may be located in a state’s court opinions (also known as its common law or case law) or in its statutes.

In New Hampshire, easements are recognized as non-possessory rights to use another person's land for a specific purpose. Easements can be created in various ways, including express grants in deeds or other legal documents (express easements), by implication from the circumstances of the creation of the easement (implied easements), by continuous and uninterrupted use over a period of time without the owner's permission (prescriptive easements), out of necessity when a landlocked property requires access (easement by necessity), or when an owner has given another party reason to believe they have an easement and they have relied on that belief (easement by estoppel). Negative easements, which restrict the servient estate from performing certain actions that could affect the dominant estate, are also recognized. Utility companies often hold easements for the purpose of installing and maintaining infrastructure. The specifics of easement law in New Hampshire can be found in state statutes, such as RSA 231, which deals with highways and other public ways, and RSA 477, which pertains to conveyances of realty and interests therein, as well as in the state's common law as interpreted by New Hampshire courts.