Making account authorization and behavior programmable, enabling features such as alternative authentication, recovery policies, batching, and sponsored execution.

Polygon's interoperability layer aimed at unifying liquidity across Polygon chains.

A blockchain dedicated to one application or ecosystem, trading shared liquidity for control.

A hash-locked exchange that either completes both legs or neither, used across chains or pairs.

An Actively Validated Service on EigenLayer, a sidecar network that borrows Ethereum restaked security.

Temporary data space introduced by EIP-4844 for rollup batches. Cheaper than calldata, pruned after weeks.

A website that decodes blocks, transactions, and contracts for humans.

A protocol that locks or burns an asset on one chain and mints or unlocks a representation on another.

An ERC-4337 node that packs user operations into a single transaction for the EntryPoint contract.

A bridge pattern that destroys coins on the source and creates them on the destination so supply stays constant.

Immutable input bytes on an Ethereum transaction. Rollups used it for data before blobs.

The official bridge of an L2 or chain, usually the safest path for that asset's native representation.

Chainlink's Cross-Chain Interoperability Protocol for moving tokens and messages across networks.

Solana's metering for how much work a transaction may consume.

The part of a stack that agrees on the next block, such as Ethereum's Beacon Chain.

A network specialized in data availability, such as Celestia.

Ethereum's roadmap for cheap blob space so rollups can post data without using expensive calldata.

Checking randomly selected pieces of encoded block data to gain confidence that enough data is available for reconstruction without downloading every piece.

zkSync's branding for a network of interoperable ZK chains.

The part of a stack that runs transactions and updates state, such as Ethereum's EVM client.

A protocol path for submitting a transaction through a settlement layer or alternative queue when a rollup sequencer does not include it normally.

Hash Timelock Contract. The primitive behind Lightning and many atomic swaps.

Inter-Blockchain Communication, the Cosmos standard for authenticated packet passing between chains.

A service that reads chain logs and stores them in a queryable database so apps do not scan every block.

The ability of chains and apps to pass assets and messages without a trusted spreadsheet in the middle.

The common request format for Ethereum-style node APIs.

A bot that calls permissionless functions (liquidations, harvests, limit orders) when conditions are met.

The time from broadcast to a usable confirmation, distinct from theoretical throughput.

A network that provides shared security or messaging so many Layer 1s can plug in, such as Polkadot or Cosmos.

A base blockchain that settles its own transactions, such as Bitcoin, Ethereum, Solana, or the XRP Ledger.

A network built on a Layer 1 that processes transactions off the base chain and posts proofs or data back to it.

An interoperability protocol that uses oracles and relayers to pass messages between chains.

A compact proof that a transaction or state is in a header a light client already trusts.

Bitcoin's payment-channel network for cheap, fast transfers that settle back to L1 when channels close.

A design that splits execution, consensus, settlement, and data availability across specialized layers.

A chain that handles execution, settlement, and data availability together, like Solana's design bet.

An ERC-4337 contract that sponsors gas so a user can pay in tokens or transact for free under a policy.

A state channel used for repeated payments, the Lightning Network being the best-known example.

An earlier L2 design that commits roots to L1 and relies on exits. Largely superseded by rollups.

An assurance about a transaction's expected inclusion, ordering, or execution given before the blockchain's ordinary confirmation or finality process completes.

The service that builds validity proofs for a ZK rollup or zkVM.

A party that submits someone else's transaction and may pay gas, used in meta-transactions and bridges.

Solana accounts that hold enough SOL to avoid being garbage-collected.

A scaling system that executes transactions outside its settlement chain and publishes commitments plus sufficient data, using fraud proofs or validity proofs to enforce state-transition rules.

Remote procedure call. The API wallets and apps use to read chain state and broadcast transactions.

The party that orders L2 transactions. A centralized sequencer is fast and is also a censorship point.

The layer that makes transfers final and resolves disputes. For many L2s that layer is Ethereum.

Splitting state or execution across many committees so the network scales beyond one machine.

A sequencer set shared across many rollups to improve censorship resistance and interoperability.

A separate chain with its own validators that bridges assets to a parent chain. Security is independent.

An off-chain agreement where two or more parties update state and only settle the last version on-chain.

OP Stack's vision of many L2s sharing standards, bridges, and governance gravity.

How many transactions a network can settle per second under its current limits.

A ceremony that creates parameters for some SNARKs. If every participant deletes their secret, the system stays sound.

A bridge design that locks coins on a parent chain and unlocks them later when a proof is shown.

A helper that watches Lightning or channel state so a counterparty cannot cheat while you are offline.

Cross-Consensus Messaging, Polkadot's format for messages between parachains and the relay chain.

A proof that a statement is true without revealing the secret that makes it true.

A rollup that posts a validity proof so L1 can check the new state without re-executing every trade.