HTTPS (Hypertext Transfer Protocol over SSL) is an extension of HTTP protocol that supports encryption for increased safety.
HTTPS is not an independent protocol. It is plain HTTP, running on top of SSL or TLS cryptographic protocols. Because of this, it provides protection against attacks based on listening to a network connection, provided that the encryption tools and a trusted server certificate are used.
Unlike HTTP with TCP port 80, TCP port 443 is used for HTTPS by default.