HTTP (Hypertext Transfer Protocol) is the protocol used by the web to transmit data between web browsers and servers, typically using port 80. HTTPS (HTTP Secure) is the secure version of HTTP, encrypting data to enhance security during transmission, using TLS (Transport Layer Security) or SSL (Secure Sockets Layer); it commonly uses port 443.

The primary difference between the two is that HTTPS incorporates encryption to protect data integrity and privacy, which HTTP does not provide. This encryption makes HTTPS crucial for handling sensitive transactions, like online banking or shopping, ensuring that data cannot be easily intercepted by third parties.