SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols used to secure data communication over the internet. These protocols ensure that the data transmitted between a client (such as a web browser) and a server is encrypted and authenticated, thereby protecting it from unauthorized access.

The SSL/TLS protocol works by establishing a secure connection between the client and the server through a series of handshakes. During this process, the client and server agree on a set of encryption algorithms and keys to use for the session, and then they use these keys to encrypt and decrypt the data being transmitted.

SSL/TLS is widely used to secure online transactions such as online banking, e-commerce, and email communication. When a website uses SSL/TLS, it is indicated by the "https" protocol in the website URL and a padlock icon in the browser's address bar. This indicates to the user that the website is secure and their data is protected.

In summary, SSL/TLS is a cryptographic protocol used to secure data communication over the internet. It encrypts and authenticates data transmitted between a client and a server, protecting it from unauthorized access.