Rollup
A Layer 2 that executes transactions off-chain and rolls up thousands into a single proof posted to the main chain.
A rollup does the heavy computation off-chain, then batches thousands of transactions into one compressed update that gets posted to the Layer 1. Users get main-chain security at a fraction of the cost.
Optimistic vs zero-knowledge
Optimistic rollups assume transactions are valid until challenged — anyone can prove a fraud for a reward. Zero-knowledge (ZK) rollups generate a cryptographic proof that every batch is valid, verified instantly by the base chain. The trade-off is complexity and finality time.
Why rollups reshape metrics
A single rollup can process more activity than the base chain itself. Layer 2 ecosystems explain a large share of “on-chain” volume, so honest comparisons account for activity flowing across both layers.
Related terms
Layer 2, Layer 1, Gas Fees, Smart Contract, Proof