# MevETH PBS Explainer [TOC] ![](https://hackmd.io/_uploads/B1hTh9LkT.png) > Schematic representation of transaction and block propagation with Proposer Builder Separation. ## Overview - (1) Searchers receive transactions from the P2P layer and generate transaction bundles using their specific MEV extraction knowledge. - (2) These bundles are then sent to one or more builders. - (3) Builders, who also receive transactions from the P2P layer, bundle blocks considering the transactions and bundles from searchers, guided by their local profit maximization algorithm. - (4) Builders connect with relays and send new maximum profit blocks to these relays as they’re discovered. - (5) Upon request, relays share the status of the maximum profit bid with the next block proposer. - (6) The block proposer, who receives transactions from the P2P layer as well, decides which block to mine based on the relay information and their own interests. - (7) If the block proposer chooses the block from the relay, they return the signed block header, prompting the relay to share the actual block. System Model PBS distributes the responsibilities of transaction bundling, sequencing, and block creation among the following parties. searchers These entities, driven by profit, crawl the blockchain state and other data sources to find lucrative opportunities such as arbitrage [8], liquidations [11, 13], and sandwich attacks [7, 17, 20]. builders: The primary role of builders is to retrieve bundles of transactions from searchers and create blocks. Block proposers, in turn, select the most valuable blocks the builders offer for further propagation. relays: Relays act as intermediaries between the block proposer and the block builder. Their main function is to transmit the most profitable block to the proposer while establishing the necessary trust between the two parties. proposers: Proposers are entities that stake their ETH to propose and vouch for blocks. In the context of the former Proof of Work paradigm, proposers can be likened to miners. In this paper, we primarily use the term "proposers" and largely ignore the process of block attestation ``` ```