# Rollup

> A type of layer 2 that bundles many transactions together and writes a summary back to the main chain.

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

## Definition

A rollup is the most common kind of layer 2. It runs transactions on its own faster, cheaper network and then 'rolls up' the results into a compact proof or batch that is posted to the main chain.

There are two main flavours. Optimistic rollups assume the batch is correct unless someone proves otherwise. Zero-knowledge rollups attach a cryptographic proof so anyone can check immediately.

## 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.
- [Ethereum](https://fudfomo.co/glossary/ethereum): A blockchain that lets developers build apps and issue tokens. Often called a programmable money platform.
- [Bridge](https://fudfomo.co/glossary/bridge): A tool that lets you move tokens from one blockchain to another.

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