Secure Sockets Layer (SSL) is an Internet security protocol that encrypts data to ensure secure communication between devices over a network. Although SSL was replaced by an updated protocol called TLS (Transport Layer Security) some time ago, "SSL" is still a commonly used term for. Secure Sockets Layer (SSL) certificates, sometimes called digital certificates, are used to establish an encrypted connection between a browser or user's computer and a server or website. They are commonly used in web browsing and email.