Legal deposit is a legal requirement that a person or group submit copies of their publications to a repository, usually a library. The number of copies required varies from country to country. Typically, the national library is the primary repository of these copies. In some countries there is also a legal deposit requirement placed on the government, and it is required to send copies of documents to publicly accessible libraries.

A library is a collection of books, and possibly other materials and media, that is accessible for use by its members and members of allied institutions. Libraries provide physical or digital materials, and may be a physical location, a virtual space, or both. A library's collection normally includes printed materials which may be borrowed, and usually also includes a reference section of publications which may only be utilized inside the premises. Resources such as commercial releases of films, television programmes, other video recordings, radio, music and audio recordings may be available in many formats. These include DVDs, Blu-rays, CDs, cassettes, or other applicable formats such as microform. They may also provide access to information, music or other content held on bibliographic databases.