HTTPS
Hypertext Transfer Protocol Secure (HTTPS) is an extension of the Hypertext Transfer Protocol (HTTP) for secure communication over a computer network, and is widely used on the Internet. In HTTPS, the communication protocol is encrypted using Transport Layer Security (TLS), or, formerly, its predecessor, Secure Sockets Layer (SSL). The protocol is therefore also often referred to as HTTP over TLS, or HTTP over SSL.
Secure Hypertext Transfer Protocol
This means that HTTPS implementations without Server Name Indication (SNI) support require a separate IP per DNS name, and all HTTPS implementations require a separate port (usually 443 vs. HTTP's standard 80) for unambiguous use of encryption (treated in most browsers as a separate URI scheme, "https://").