What is a bridge in crypto?

You have tokens on one network, but the app you want to use runs on another? It’s not enough to send them to an address on the second network. Each blockchain keeps its own transaction record. A bridge connects these separate systems, like a service that coordinates pickups and deliveries between two islands.

In a common model, you deposit tokens into a smart contract on the original network. They are locked there and, once the deposit is confirmed, a corresponding representation of them, a wrapped token, is issued on the second network. To go back, the representation is burned and the original tokens are released. So the same token doesn’t literally travel from chain to chain.

Not all bridges work this way. Some use available reserves, i.e. liquidity, to deliver the recipient tokens that already exist on the destination network. There are also bridges that pass messages and instructions, not just value.

Why it matters

Bridges let you use apps on different networks and move funds between them. This also covers connections to Layer 2 networks, where transactions may have lower fees.

The critical question, in our view, is who confirms that the transfer was carried out correctly. Depending on the design, you may be relying on specific operators, a group of validators or cryptographic proofs. The security of the two blockchains doesn’t on its own guarantee the security of the bridge connecting them.

What to watch out for

A bug in the code or a compromise of the admin keys can lead to a loss of funds. If the reserves backing a wrapped token are lost, your ability to redeem it is affected too. A security audit helps, but it isn’t a guarantee.

Before confirming, check the destination network and the exact token you’ll receive, not just its name or ticker. Also factor in the bridge’s fees, the transaction costs (gas) on both networks and any waiting time. Having the same wallet address on two networks doesn’t mean a simple send automatically does the bridge’s job.