SSL/TLS

SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) are protocols that encrypt communication between two computers, most commonly between a browser and a website (HTTPS). They keep data private, prevent tampering and verify the server's identity.

During the TLS handshake, the server presents a certificate issued by a trusted certificate authority, and both sides agree on encryption keys. SSL is obsolete and insecure; modern systems use TLS 1.2 and TLS 1.3, although people still commonly say "SSL certificate".