Landlord / Tenant refers to the relationship between (1) the owner or lessor (landlord) of residential or commercial real property known as the leased premises and (2) the occupant or lessee (the tenant) of the leased premises—often a home or office building or space. This relationship is defined by the (usually written) lease agreement signed by the landlord and tenant, and the laws governing the landlord / tenant relationship—which are usually located in a state’s statutes.

A residential or commercial lease of real property (real estate) allows the tenant or lessee to use the property and the improvements on the property—generally a building structure such as a home, office, store, or warehouse, for example—for a stated purpose (such as for a residential dwelling or the operation of a hair salon) and for a fixed period of time (the term of the lease), in exchange for the payment of rent.

Personal property—including automobiles, computers, heavy equipment, machines, home appliances, and other tangible, movable goods—may also be leased, but the parties to a lease of personal property (as opposed to real property) are not referred to as landlord and tenant, but as lessor and lessee.

In Oregon, the landlord-tenant relationship is governed by state statutes that outline the rights and responsibilities of both parties. These laws cover various aspects of the rental agreement for both residential and commercial properties. The lease agreement, which is typically in written form, sets the terms for the tenant's use of the property, the duration of the lease, and the amount of rent to be paid. Oregon's Residential Landlord and Tenant Act specifically regulates residential leases, providing protections for tenants such as the requirement for habitable living conditions, rules for the handling of security deposits, notice periods for rent increases and terminations, and procedures for eviction. Commercial leases are also governed by state law, but with fewer statutory protections compared to residential leases, often leaving more terms to be defined by the lease agreement itself. It's important to note that while the terms 'landlord' and 'tenant' are used for real property leases, parties to a personal property lease are referred to as 'lessor' and 'lessee', and such agreements are subject to different regulations.