SSL (Secure Sockets Layer) is a protocol for establishing secure and encrypted connections between a web server and a web browser. SSL is used to secure sensitive information, such as login credentials, credit card information, and personal data, that is transmitted over the internet.

When an SSL connection is established, the browser and server encrypt all data that is transmitted between them. This means that any data that is intercepted by third parties is unreadable and cannot be used maliciously. This provides a secure and private connection, and helps to protect the confidentiality and integrity of sensitive data.

To use SSL, a website must have an SSL certificate installed on its server. SSL certificates are issued by trusted third-party organizations called Certificate Authorities, which verify that the website is authentic and belongs to the entity it claims to represent. When a user visits a website with an SSL certificate, the browser checks the certificate to ensure that it is valid and that the website is safe to access.

In recent years, SSL has been replaced by the newer and more advanced TLS (Transport Layer Security) protocol. TLS provides stronger encryption and better security features than SSL, and is used in many modern web browsers and websites. However, the term SSL is still commonly used to refer to the process of establishing secure connections between web servers and browsers.