GnuTLS is a modern C library that implements the standard network security protocol Transport Layer Security (TLS), for use by network applications. GnuTLS is developed for GNU/Linux, but works on many Unix-like systems and comes with a binary installer for Windows. The GnuTLS library is distributed under the terms of the GNU LGPL 2.1+. The "extra" GnuTLS library (which contains TLS/IA support, LZO compression and Libgcrypt FIPS-mode handler), the OpenSSL compatibility library, the self tests and the command line tools are all distributed under the GNU GPL 3.0+. The manual is distributed under the GNU FDL 1.3+.