# EVM

## Introduction

This document outlines the main functionalities of the Brotocol Bridge as deployed on EVM-compatible blockchains. The core aspects of the bridging operation are implemented in the `BridgeEndpoint` contract, which acts as the main entry and exit point for cross-chain operations, ensuring that assets are securely locked, minted/burned, transferred, and released. The `BridgeEndpointWithSwap` contract extends this functionality by incorporating swaps, allowing bridging and swapping to occur in within a single transaction.

The Brotocol ecosystem offers two main features in its EVM implementation:

* The **bridging of ERC-20 assets**: these contracts interact with Brotocol's off-chain protocol actors to allow the transfer of assets back and forth between EVM-compatible blockchains and Stacks.
* The **swapping of tokens in the bridging process** via external liquidity aggregators.

### EVM Chain Bridge

![This is a simplified representation on the EVM Chain Bridge's main goal.](/files/fwfNR3NqW1uSBXo7cHed)

\*To see more information on the registry contract, see the [auxiliary contracts section](#auxiliary-contracts).

#### Bridge Endpoint

* Contract names: `BridgeEndpoint`, `BridgeEndpointWithSwap`.
* [Complete technical documentation](/developers/brotocol-contracts/chains/evm/bridgeendpoint.md)

This endpoint's main responsibility is serving as the entry and exit point for assets moving along Brotocol's cross-chain bridge. Sometimes, it also involves swapping to other tokens as part of the peg-in process.

### Auxiliary Contracts

These contracts do not include the implementation of any core functionality but they serve as a support for other contracts to facilitate calculations and common storage management.

* **Bridge Registry**: this contract keeps a record of approved tokens, validators, relayers and fees. It also keeps a record of the generated orders and their statuses. Its latest version can be found at `BridgeRegistry.sol`.


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