A protocol is a set of official rules or procedures for how something should be done, especially in formal situations. In diplomacy, protocol determines who enters a room first, where people sit at state dinners, and how officials greet each other. These rules might seem picky, but they prevent misunderstandings and show respect between countries.

The word appears in many contexts. In science, an experimental protocol lists every step researchers must follow so others can repeat their work exactly. If you're testing which fertilizer helps plants grow fastest, your protocol might specify: use identical pots, water each plant with exactly 100 milliliters daily, and measure growth every three days. Following the protocol ensures your results are reliable.

In medicine, protocols guide doctors through complex decisions. A hospital might have a protocol for treating someone with a severe allergic reaction: first do this, then check that, then proceed to the next step. These standardized procedures help ensure quality care.

In computing, protocols are agreed-upon rules that let different devices communicate. The internet runs on protocols that specify exactly how data gets broken into packets, sent across networks, and reassembled at its destination. Without these rules, your computer couldn't talk to servers halfway around the world.

When someone says “that's not proper protocol,” they mean you've skipped or ignored an established procedure that exists for good reason.