What is a protocol and why are protocols necessary for network communication?

A protocol is the set of rules a communication follows; without shared rules, sender and receiver cannot reliably understand each other.

A protocol is a set of rules that communications will follow.

Why protocols are necessary:

• All communications are governed by protocols
• Protocols define the rules that communications follow
• These rules vary depending on the specific protocol being used

Just like humans need agreed-upon rules to communicate effectively (language, grammar, turn-taking), network devices need protocols to exchange data successfully.

Go deeper:

• Communication protocol — full overview of what protocols define and why layering matters.
• RFC 1122 — Requirements for Internet Hosts — a primary-source example of how protocol rules are precisely specified.