SHA-1 is a SHA family algorithm invented in 1995 by U.S. National Security Agency . It is also known as SHA, OpenPGP.Digest.2 and is mainly used in Microsoft XBOX, TLS, SSL, PGP, SSH, S/MIME, IPsec.

The digest (hash generated by this algorithm) is 160 bits (20 Bytes) in length.

You can read more about it on this page.