Bridging basics
Metal L2 is a "Layer 2" system and is fundamentally connected to Ethereum. However, Metal L2 is also a distinct blockchain with its own blocks and transactions. App developers commonly need to move data and tokens between Metal L2 and Ethereum. This process of moving data and tokens between the two networks is called "bridging".
Sending tokens
One of the most common use cases for bridging is the need to send ETH or ERC-20 tokens between Metal L2 and Ethereum. Metal L2 has a system called the Standard Bridge that makes it easy to move tokens in both directions. If you mostly need to bridge tokens, make sure to check out the Standard Bridge guide.
Sending data
Under the hood, the Standard Bridge is just an application that uses the Metal L2 message passing system to send arbitrary data between Ethereum and Metal L2. Applications can use this system to have a contract on Ethereum interact with a contract on Metal L2, and vice versa. All of this is easily accessible with a simple, clean API.
Next steps
Ready to start bridging? Check out these tutorials to get up to speed fast.