Which protocol is primarily used for secure web browsing?

The primary protocol used for secure web browsing is HTTPS, which stands for Hypertext Transfer Protocol Secure. HTTPS is an extension of HTTP, the foundational protocol used for transferring data over the web. The addition of 'Secure' indicates that HTTPS incorporates two key elements: SSL (Secure Sockets Layer) or TLS (Transport Layer Security). These security protocols encrypt the data exchanged between a user's browser and the web server, ensuring that sensitive information such as login credentials, credit card numbers, and personal data remains confidential and protected from eavesdropping or tampering.

In contrast, while HTTP is the standard protocol for web traffic, it does not provide any encryption, making it less secure for browsing sites that require user authentication or process sensitive information. FTP, or File Transfer Protocol, is designed for transferring files over a network, and is not related to web browsing. SMTP, or Simple Mail Transfer Protocol, is used primarily for sending and receiving emails, and also has no direct application in secure web browsing. Hence, HTTPS is the definitive choice for secure web communications.