The domain name edu is a sponsored top-level domain (sTLD) in the Domain Name System of the Internet. Its name is derived from education, indicating its intended use as a name space for educational institutions, primarily those in the United States. Although not officially mandated for much of the domain's existence, in practice it has been used primarily for U.S.-based four-year universities. Starting in 2001, it was officially restricted to accredited post-secondary institutions and organizations that are accredited by nationally recognized accrediting agencies.