Bridging Basics
Although OP Mainnet is an L2 (and therefore fundamentally connected to Ethereum), it's also a separate blockchain system. App developers commonly need to move data and assets between OP Mainnet and Ethereum. We call the process of moving data and assets between the two networks "bridging".
Sending Tokens
For the most common usecase, moving tokens around, we've created the Standard Token Bridge guide. The Standard Token Bridge is a simple smart contract with the functionality you need to move tokens between OP Mainnet and Ethereum. It also allows you to easily create L2 representations of existing tokens on Ethereum.
Sending Data
If the Standard Token Bridge doesn't fully cover your usecase, you can also send arbitrary data between L1 and L2. You can use this functionality to have a contract on Ethereum trigger a contract function on OP Mainnet and vice versa. We've made this process as easy as possible by giving developers a simple API for triggering a cross-chain function call. We even use this API under the hood (opens in a new tab) inside the Standard Token Bridge.
Next Steps
For additional bridging use cases, please check out these tutorials: