The living knowledge base for Layer-2 infrastructure
The dominant Layer-2 scaling pattern. Transactions are executed off-chain and compressed into batches. A cryptographic proof of batch validity is posted to Layer 1 for verification and settlement.
Two parties lock funds on-chain and transact off-chain indefinitely. Only the opening and closing transactions touch Layer 1.
Independent blockchains connected to Layer 1 via a bridge. They maintain their own consensus but derive some security from the parent chain.
Like rollups, but with off-chain data availability. Proofs are posted to Layer 1, but the full transaction data is stored elsewhere. The tradeoff: lower cost, weaker data guarantees.
Zero-knowledge proofs are the cryptographic engine of zkRollups. A prover constructs a mathematical proof that a set of state transitions is valid. The proof is succinct -- verifying it requires orders of magnitude less computation than re-executing the transitions. This asymmetry between proving and verifying is the fundamental insight that makes Layer-2 scaling possible.
Optimistic rollups take a different approach: instead of proving validity upfront, they assume all transactions are valid and rely on a challenge period during which anyone can submit a fraud proof to contest an invalid state transition. The tradeoff is latency: withdrawal times are longer because the system must wait for the challenge window to close.
All paths through the wiki converge here: Layer-2 is not a single technology but an ecosystem of approaches, each making different tradeoffs between security, cost, latency, and data availability. The quest for scale is a quest for the right tradeoff at the right time.
layer-2.wiki