What is the underlying protocol for HTTPS?

The underlying protocol for HTTPS is SSL, which stands for Secure Sockets Layer. HTTPS, or Hypertext Transfer Protocol Secure, is essentially HTTP but with an added layer of security. SSL encrypts the data transmitted between a user's browser and a web server, ensuring that sensitive information, such as passwords and credit card numbers, remains private and secure from potential eavesdroppers.

SSL enables secure communication by facilitating the establishment of a secure channel over an insecure network, which is crucial for protecting data against interception and tampering. While SSL has been succeeded by TLS (Transport Layer Security) in terms of standard protocol, the term SSL is still commonly used to refer to both SSL and TLS in the context of secure communications.

The other protocols mentioned do not serve the same purpose: ICMP (Internet Control Message Protocol) is primarily used for error messages and operational queries, while UDP (User Datagram Protocol) is a transport layer protocol that does not provide inherent security features. Therefore, recognizing SSL as the foundational protocol for HTTPS highlights its critical role in web security.