A lease is a contract conferring a right on one person (called a tenant or lessee) to possess property belonging to another person (called a landlord or lessor) to the exclusion of the owner landlord. It is a rental agreement between landlord and tenant. The relationship between the tenant and the landlord is called a tenancy, and the right to possession by the tenant is sometimes called a leasehold interest. A lease can be for a fixed period of time (called the term of the lease) but may be terminated sooner. The consideration for the lease is called rent or the rental.

A lease should be contrasted to a license, which may entitle a person (called a licensee) to occupy property, but which is subject to termination at the will of the owner of the property (called the licensor).

Under normal circumstances, owners of property are at liberty to do what they want with their property, including dealing with it or handing over possession of the property to a tenant for a limited period of time. However, if an owner has surrendered possession to another (ie the tenant) then any interference with the quiet enjoyment of the property by the tenant in lawful possession is itself unlawful.

Similar principles apply to real property as well as to personal property, though the terminology would be different. Similar principles apply to sub-leasing, that is the leasing by a tenant in possession to a sub-tenant. The right to sub-lease can be expressly prohibited by the main lease.

Fixed-term tenancy or tenancy for years

A fixed-term tenancy or tenancy for years lasts for some fixed period of time. Despite the name tenancy for years, such a tenancy can last for any period of time — even a tenancy for one week would be called a tenancy for years. At Common law the duration did not need to be certain, but could be conditioned upon the happening of some event, (e.g. "until the crops are ready for harvest", "until the war is over"). In many jurisdictions that possibility has been partially or totally abolished.

A fixed term tenancy comes to an end automatically when the fixed term runs out, or, in the case of a tenancy that ends on the happening of an event, when the event occurs.

Periodic tenancy

A periodic tenancy, also known as a tenancy from year to year, month to month, or week to week, is an estate that exists for some period of time determined by the term of the payment of rent. An oral lease for a tenancy of years that violates the Statute of Frauds (by committing to a lease of more than--depending on the jurisdiction--one year without being in writing) may actually create a periodic tenancy, the construed term being dependent on the laws of the jurisdiction where the leased premises are located. In many jurisdictions the "default" tenancy, where the parties have not explicitly specified a different arrangement, and where none is presumed under local or business custom, is a month-to-month tenancy.