Glossary
Proposer-Builder Separation (PBS)
An Ethereum design pattern that splits block proposing (validators) from block building (specialized actors who order transactions and extract MEV).
Without PBS, every validator both proposes blocks and decides their contents — which creates centralizing economies of scale for whoever can extract the most MEV. PBS separates the two roles: proposers commit to whichever block header pays them the most, and specialized builders compete to construct that block.
The validator runs cheap consumer hardware; the builder runs heavy infrastructure. Today PBS is realized via MEV-Boost (out-of-protocol). Enshrined PBS ("ePBS") would move the mechanism into the protocol itself.