SSL and TLS Protocols

SSL stands for Secure Sockets Layer and was initiated by Netscape, SSLv1, SSLv2 and SSLv3 are the 3 versions of this protocol. After SSLv3, SSL was renamed to TLS.

TLS stands for Transport Layer Security and started with TLSv1 which is an upgraded version of SSLv3.

Those protocols are standardized and described by RFC.

OpenSSL provides implementation for those protocols and is often used as the reference implementation for any new feature.