The primary distinction between HTTP and HTTPS lies in their security features. HTTPS, or HTTP Secure, encrypts the data transmitted between the user's browser and the web server using SSL (Secure Sockets Layer) or TLS (Transport Layer Security) protocols. This encryption protects sensitive information, such as login credentials and personal details, from interception by malicious actors. As a result, HTTPS is essential for secure online transactions and maintaining users' privacy, leading to its increasing adoption across websites.