# Sidechain

> A separate blockchain that runs alongside a main chain and is connected by a bridge.

Canonical URL: https://fudfomo.co/glossary/sidechain
Source: What The Block! Dictionary v1.0 (last updated 2026-04-25), browsable at https://wtb.fudfomo.co.

## Definition

A sidechain is its own blockchain that is linked to a larger one, but does not inherit that chain's security. It has its own validators and its own rules.

Sidechains can be cheaper and faster, but if the sidechain is attacked, the main chain cannot help you recover funds. They are different from rollups, which do post proofs back to the main chain.

## Related terms

- [Layer 2](https://fudfomo.co/glossary/layer-2): A faster, cheaper network built on top of a layer 1 like Ethereum. Borrows the main chain's security.
- [Bridge](https://fudfomo.co/glossary/bridge): A tool that lets you move tokens from one blockchain to another.
- [Rollup](https://fudfomo.co/glossary/rollup): A type of layer 2 that bundles many transactions together and writes a summary back to the main chain.

## See the full catalogue

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