Self storage (a shorthand for "self-service storage," and also known as "device storage") is an industry that rents storage space (such as rooms, lockers, containers, and/or outdoor space), also known as "storage units," to tenants, usually on a short-term basis (often month-to-month). Self-storage tenants include businesses and individuals.

When discussing why a storage space is rented, industry experts often refer to "4Ds of life" (death, divorce, downsizing, and dislocation; the latter can refer to either the renter relocating to another area and needing space to store items until they can be moved to the new location, or a subsequent marriage resulting in the couple having duplicate items).