What is a network protocol?
Answer
A network protocol is a set of rules and conventions that govern how devices communicate over a network. Protocols define the format of messages, the sequence of exchanges, error handling, and how to establish and terminate connections. Without protocols, devices from different manufacturers could not communicate. Protocols exist at every OSI layer: Physical (Ethernet, Wi-Fi), Data Link (Ethernet 802.3, PPP), Network (IP, ICMP, OSPF, BGP), Transport (TCP, UDP), Application (HTTP, FTP, SMTP, DNS, SSH). Protocols are typically defined in RFCs (Request for Comments) published by IETF (Internet Engineering Task Force). Standardization allows interoperability — your MacBook can browse a website on a Windows server because both follow the same HTTP, TCP, and IP protocols.