Which port is used for secure HTTP (HTTPS)?

The correct answer, 443, is the designated port for secure HTTP (HTTPS). HTTPS is a protocol used for secure communication over a computer network, particularly the internet. This secure version of HTTP implements transport layer security (TLS) to encrypt the data transmitted between a user's browser and the website, protecting it from eavesdropping and tampering.

Port 443 is specifically assigned for HTTPS traffic, allowing web servers and browsers to establish secure connections. When a user accesses a website using HTTPS, their browser automatically communicates with the server through this port, ensuring that the session is encrypted and secure.

In contrast, the other ports mentioned serve different purposes: port 53 is used for DNS (Domain Name System) queries, port 80 is reserved for standard unencrypted HTTP traffic, and port 110 is associated with the retrieval of emails using the Post Office Protocol version 3 (POP3). Therefore, understanding the specific function of port 443 is critical for recognizing its role in securing web communications.