Hypertext Transfer Protocol Secure (HTTPS) is a variant of the standard web Hypertext Transfer Protocol (HTTP) that adds a layer of security on the data in transit through a Secure Sockets Layer (SSL) or Transport layer security (TLS) Protocol connection.
HTTPS enables encrypted communication and secure connection between a remote user (i.e., Client and the primary web Server.
See: RFC2818 - HTTP Over TLS (HTTPS)
Source https://www.techopedia.com/definition/5361/hypertext-transport-protocol-secure-https