Quick answer
A rollup batches transactions and uses a base blockchain for settlement, data availability, or verification.
What is Rollup?
A rollup executes many transactions outside the base chain and posts enough information or a proof for the base chain to settle the result. Optimistic and zero-knowledge designs use different verification and withdrawal assumptions.
The useful way to approach this term is to separate its definition from the assumptions people often attach to it. In crypto, the same word can appear in a protocol rule, a user interface, a market-data label, or a marketing claim. Check which layer the explanation is describing.
Why does rollup matter?
Rollups can change fees and throughput, but readers must understand bridge trust, sequencer dependence, data availability, proof timing, and application compatibility before moving assets.
Concrete example
See it in a real situation
A rollup operator combines hundreds of transfers into one batch, posts data to the base chain, and later finalizes the batch under the rollup’s proof rules.
Common misconceptions
What this term does not mean
- Rollup does not mean every transaction is instantly final on the base chain.
- Two rollups using the same base chain can have different withdrawal and upgrade risks.
Related terms
Sources and further reading
Definitions are written for education and checked against the sources below where relevant. A source can explain a protocol or rule without endorsing every product built around it.