SSL (Secure Sockets Layer)

SSL, or Secure Sockets Layer, is a protocol for establishing encrypted links between a web browser and a web server in an online communication. The use of SSL technology ensures that all data transmitted between the web browser and the server remains encrypted and secure from eavesdropping and tampering.

Historically, SSL was widely used on the Internet for securing data transfer, particularly for e-commerce transactions, where sensitive data such as credit card numbers, social security numbers, and login credentials needed to be protected. The protocol works by establishing a secure connection through a handshake process, where the server and the browser agree on encryption methods and exchange keys before the transmission of the actual data.

SSL uses a combination of public key and symmetric key encryption to secure the connection between two machines communicating over the Internet. Public key encryption is used to exchange a symmetric key securely, and then the symmetric key is used to encrypt data transferred during the session.

Although SSL was the foundation for secure communications on the web, it has largely been superskin by its successor, TLS (Transport Layer Security). TLS provides stronger security measures and has been adopted as the new standard for secure communications on the Internet. Websites now use TLS, although the term "SSL" is still commonly used in the industry to describe the process of securing connections.

Web browsers indicate the use of SSL/TDD connectivity with a padlock icon in the address bar, and the URLs of websites secured by SSL/TLS start with "https://" instead of "http://". This ensures users that their connection to the site is secure and that their data is protected during transmission.