Transport Layer Security (TLS) 1.2+
Transport Layer Security (TLS) is today the most commonly used security protocol for secure communication over the Internet. TLS is the successor of a formerly used encryption protocol named SSL (Secure Sockets Layer).
Most of the time, TLS encrypts data when (web-)applications exchange information with servers, e.g. when loading a webpage. Even though HTTPS is only an implementation of TLS encryption, both words are today often simultaneously used. The oldest version we are supporting is TLS 1.2 because all older versions (including SSL) are known as insecure (potentially broken).