Protocol Layer

The protocol layer is the part of a blockchain or network stack where the core rules live: what a valid transaction looks like, how blocks are built, how nodes talk to each other and how they reach agreement through a consensus mechanism. Everything above it, from wallets to exchanges and decentralised apps, relies on those rules without changing them. In crypto writing the phrase is often used loosely as a synonym for the base chain, or layer 1, and set against the application layer where users interact. Changing the protocol layer usually needs broad agreement among developers and node operators, and may require a hard fork. The term comes from general networking, where layered models separate the rules for moving data from the programs that use it.