What is a sidechain?

Imagine a main road and a parallel one that takes some of the traffic but has its own flow and checks. That’s roughly how a sidechain works: it executes transactions on its own network, without every action having to be recorded on the main chain.

The connection is usually made through a bridge. In a typical setup, you lock an asset on the main chain and receive a corresponding representation of it on the sidechain. To go back, the representation is burned or locked and the original asset is released, according to the bridge’s rules. In other words, the same coin doesn’t “travel” from one chain to the other.

A sidechain can have different block times, fees and app capabilities. Its transactions are checked by the participants in its own consensus mechanism, i.e. the system the network uses to agree on which transactions are valid.

Why it matters

If you use crypto, a sidechain can offer lower fees, faster service or features the main chain doesn’t support. These depend on the network’s design and usage; they aren’t guaranteed.

The crucial difference from Layer 2 solutions, such as rollups, is security. A sidechain doesn’t automatically inherit the main chain’s security. Rollups are designed so that the main chain enforces the validity of their state through proofs or challenge mechanisms. With a sidechain, you trust its own mechanism and, on top of that, the link between the networks.

What to watch out for

We separate two questions: who controls the sidechain, and who can release the assets held in the bridge? A small number of validators or operators can hold a lot of power. A bridge hack can leave the tokens on the sidechain without the backing you’d expect.

In practice, also check that your wallet and exchange support that specific network. The same token name or the same address format doesn’t mean a compatible transfer. You may need a different coin to pay fees, and returning to the main chain may involve extra cost or waiting.