Scaling glossary
Rollups, sequencers and data availability. Make sense of the Layer 2 conversation and the tradeoffs behind a faster, cheaper transaction.
Blob
A specialized Ethereum data payload with a separate fee market and temporary availability rules, used by systems such as rollups.
Bridge
A mechanism for moving assets, asset representations or messages between blockchain environments.
Challenge period
The window during which a submitted result or withdrawal can be disputed under a protocol's rules.
Data availability
The ability to obtain the data needed to verify or reconstruct a blockchain system's state.
Fraud proof
Evidence used to demonstrate that a claimed computation or state transition is incorrect.
HTLC
A hashed time-locked contract: a conditional payment combining a secret-hash requirement with a timeout.
Layer 1
A blockchain's base network, responsible for its own consensus and canonical state.
Layer 2
A system that processes activity outside a base blockchain while relying on it for key security or settlement functions.
Lightning Network
A Bitcoin payment network that uses channels so every payment does not need its own onchain record.
Optimistic rollup
A rollup that accepts submitted execution results subject to a process for challenging invalid results.
Payment channel
A channel that updates payment balances without requiring an onchain transaction for every payment.
Rollup
A scaling system that executes transactions separately and publishes required data and commitments to a base chain.
Sequencer
A component or participant that orders transactions for execution in a scaling system.
Sidechain
A separate blockchain connected to another chain while using its own consensus security.
State channel
A system where participants exchange authorized state updates offchain and use a blockchain to enforce settlement.
Validity proof
A cryptographic proof that a claimed computation or state transition follows specified rules.
Validium
A scaling design that uses validity proofs while keeping transaction data outside the settlement chain.
Zero-knowledge rollup
A rollup that uses cryptographic validity proofs to demonstrate correct execution of transaction batches.
Looking for an earlier definition? Explore the original collection
Concept entries explain ideas. Our separate asset registry identifies coins, tokens and networks by source metadata. Sources & standards