What is Rollup?
A rollup is a Layer 2 scaling solution that executes transactions off-chain but posts compressed transaction data (and/or validity proofs) back to a Layer 1. Optimistic rollups assume validity and allow fraud proofs; zk-rollups prove validity cryptographically.
Why Rollup matters
Understanding Rollup is part of building a solid mental model of how Bitcoin, blockchain and Web3 systems actually work. Concepts in the Concepts category sit at the foundation of the broader stack — get them right and the rest is far easier.
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Related terms
- Layer 2 (L2) — A scaling network that settles to a Layer 1.
- Optimistic Rollup — A rollup that assumes validity, with a fraud-proof challenge window.
- ZK-Rollup — A rollup that proves validity with zero-knowledge cryptography.
More concepts terms
- Decentralization — Distributing control across many independent participants.
- Atomic Swap — Trustless cross-chain trade using hash time-locked contracts.
- Bridge — A protocol that moves assets or messages between chains.
- Byzantine Fault Tolerance (BFT) — A system that works even when some nodes lie or fail.
- Staking — Locking tokens to secure a network and earn rewards.
- Validator — A node that proposes and attests to blocks in PoS.
- Layer 1 (L1) — A base blockchain network with its own consensus.
- Sidechain — A separate blockchain pegged to another via a bridge.
Keep exploring
Continue with the full blockchain glossary — 136 terms in total — or read the developer blog and FAQ for deeper context.