# Introduction

Maximal Extractable Value (MEV) refers to the maximum value that block producers or validators can extract by reordering, including, or excluding transactions in a block. MEV plays a critical role in decentralized finance (DeFi), enabling strategies such as arbitrage, frontrunning, and liquidation. However, it introduces challenges like high gas costs, centralization risks, and inefficiencies.

### Transaction Supply Chain 

The **Transaction Supply Chain** in blockchain represents the lifecycle of a transaction, from creation to inclusion in a block. Each operator plays a critical role in this process:

<figure><img src="https://1795498980-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FDmGAmCQO6M4XFVxiABwZ%2Fuploads%2Fl36sXT6Yog6vmCgiLbya%2F1661989178786531.webp?alt=media&#x26;token=087c4df4-affa-483e-918e-2a541de27ebe" alt=""><figcaption><p>Mev Supply Chain Diagram</p></figcaption></figure>

* **Transaction Originator**: The user or smart contract initiating the transaction. They specify the action (e.g., swap, transfer) and attach gas fees to incentivize miners or validators.
* **Mempool**: A temporary storage for pending transactions. It serves as a queue where validators or block builders prioritize transactions based on gas fees and potential value.
* **MEV Searchers**: Specialized operators analyzing the mempool to identify profitable opportunities, such as arbitrage, frontrunning, or sandwich strategies.
* **Block Builders**: Entities responsible for assembling transactions into blocks, often selecting those with the highest gas fees or value extracted.
* **Validators/Miners**: Validate and add blocks to the blockchain, ensuring consensus and network security.
* **Transaction Recipients**: The end user or smart contract that receives the results of the transaction, completing the supply chain.