Secure Sockets Layer (SSL) is a security protocol that was widely used for establishing encrypted links between networked computers. It was initially developed by Netscape in the 1990s to secure the transmission of sensitive information, such as credit card numbers and login credentials, over the internet. However, over time, it was replaced by a more secure and improved version of the protocol, known as Transport Layer Security (TLS).
TLS is backward-compatible with SSL, meaning that SSL-enabled servers can be easily upgraded to TLS without any disruption to existing communication. The primary difference between SSL and TLS is that TLS is more secure and provides improved encryption algorithms and key exchanges. Most websites now use TLS to secure their communications and protect their users' sensitive information.