SSL (Secure Sockets Layer) is a protocol that provides secure communications on the Internet for such things as web browsing, e-mail, instant messaging, and other data transfers. Google forces HTTPS (Hypertext Transfer Protocol Secure) when your users access most services in G Suite. SSL is available for Gmail, Chat, Calendar, Google Groups for Business, Drive, and Sites.
The advantage of SSL is added security for your users. If your users access G Suite on a non-secure Internet connection, such as a public wireless or non-encrypted network, your users' accounts may be more vulnerable to hijacking. A secure connection prevents hijacking by protecting the cookie session. Cookie session hijacking refers to a situation where an impostor gains unauthorized access to cookies and seizes control of a legitimate session while it is still in progress.
Note: SSL has been superseded by Transport Layer Security (TLS). Don't worry if you see mention of SSL in G Suite. All areas that mention SSL are now using TLS.
TLS is an industry-wide standard based on Secure Sockets Layer (SSL) technology that encrypts mail for secure delivery.
G Suite supports TLS versions 1.0, 1.1, and 1.2. Learn about changing the Secure transport (TLS) compliance setting and configuring advanced settings for Gmail.