Blockchain
Rollup
Also known as: rollup chain, optimistic rollup, zk-rollup
A Layer 2 architecture that executes transactions off-chain and posts compressed batches plus validity or fraud proofs back to Layer 1.
A rollup is a Layer 2 blockchain that batches user transactions, executes them off the main chain, and posts a compressed summary back to Layer 1 with some form of validity proof. Two families exist: optimistic rollups (which post transactions as-is and allow a challenge window during which anyone can submit a fraud proof to roll back an invalid state) and zk-rollups (which post a zero-knowledge validity proof up front, giving faster finality but at higher proving cost).
Both architectures inherit L1's data-availability guarantees — the transactions themselves are stored on L1 as calldata or blob data — so a rollup's historical state can always be reconstructed from Ethereum. That's the property that makes rollups more than sidechains.
LearnCoin anchors on Base, an optimistic rollup. The choice is pragmatic: optimistic rollups have lower on-chain cost per transaction and Base specifically has strong ecosystem alignment (Coinbase, Farcaster, major stablecoin issuers). The OP Stack fraud-proof system is live as of 2024, closing the "training-wheels" concern earlier optimistic rollups carried.
Related terms