Learn in the textbookTCP/IP and Web Protocols
DefinitionHTTPS is a protocol that encrypts HTTP traffic with SSL/TLS and also lets you check that the server you are talking to is genuine.
ExplanationSSL/TLS is the mechanism that encrypts communication and authenticates servers using digital certificates. It is widely used on pages that handle information others must not see, such as passwords and credit card numbers. The URL starts with "https://", and port 443 is the usual number.
AnalogyIt is like moving messages from postcards into sealed envelopes. People handling them on the way cannot see inside, and the envelopes from the shop (the server) carry an officially certified seal, so the customer (the browser) can confirm the shop is genuine.
Memory hookThe final S stands for Secure. The name just adds one letter to HTTP, and those five letters also open the URL.