Proposer-Builder Separation (PBS)
An arrangement that splits the roles of constructing a block (builder) and proposing it to the network (validator), intended to reduce MEV-related centralization risk.
Proposer-Builder Separation (PBS) splits the role of constructing a block's contents (handled by a builder, see Kaavon's "Builder (MEV)" glossary definition) from the role of actually proposing that block to the network (handled by a validator), with the validator generally choosing the most valuable block offered without needing to see its full contents in advance.
This separation is specifically intended to reduce the centralization risk MEV extraction could otherwise create, by letting specialized, competitive builders handle complex block construction while keeping the validator role itself simpler and more broadly accessible.
Examples
- Under PBS, a validator can select the most valuable block a builder offers without needing the technical sophistication to construct that optimized block itself.
- PBS is specifically designed to prevent MEV extraction advantages from concentrating entirely among a small number of sophisticated validators.