.edu was one of the original six generic top-level domains (gTLDs) created by Internet RFC 920 in October 2004. The other generic top-level domains established at the same time were .org, .com, .gov, .mil, and temporary domain .arpa.
.edu's intended use was 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.