# The difference between Optimistic and ZK rollups — without complex terms
Rollups are a key way to scale Ethereum. But there are two different approaches: Optimistic and ZK. Both gather transactions off L1 and publish the result on Ethereum, but they do it differently. In simple terms — they have different trust logics.
### Optimistic rollups: "we believe everything is fair"
Optimistic assumes that transactions are correct by default.