What is the key difference between HTTP and HTTPS?

The key difference between HTTP and HTTPS is that HTTPS uses encryption for secure data transmission. This encryption is achieved through the use of SSL (Secure Sockets Layer) or TLS (Transport Layer Security) protocols, which provide a secure channel over an insecure network, ensuring that any data exchanged between a user's web browser and the web server is protected from eavesdropping, tampering, and man-in-the-middle attacks.

This security feature is crucial for protecting sensitive information, such as passwords, credit card numbers, and personal data, especially when conducting financial transactions or when logging into accounts. The commitment to security is what makes HTTPS essential for modern web applications and is why browsers often indicate secure connections through visual cues, like a padlock icon in the address bar.

The other choices do not accurately reflect the fundamental differences between HTTP and HTTPS. For instance, while speed can be affected by various factors, HTTPS is not inherently faster than HTTP due to the additional overhead of encryption. Similarly, the types of files supported are not dictated by whether a website uses HTTP or HTTPS; both protocols can serve the same types of content. Finally, HTTPS is not an outdated version of HTTP; rather, it is an extension aimed at providing a more secure alternative.