# Ethereum layer 2: execution elsewhere, settlement on Ethereum An Ethereum layer 2 processes activity outside Ethereum’s main execution layer while using Ethereum for important security or settlement functions. Rollups publish data and state-related commitments to Ethereum and use disputes or validity proofs. Their actual guarantees also depend on their implementation, upgrade controls, data availability and exit mechanisms. Evidence: [Scaling overview](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/index.md); [Optimistic rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/optimistic-rollups/index.md); [Zero-knowledge rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/zk-rollups/index.md) Canonical: https://degreesofsatoshi.com/encyclopedia/ethereum-layer-2/ Published: 2026-10-02 Substantively modified: 2026-10-02 Independently verified by an automated reviewer: 2026-10-02T15:10:23.134Z AI-assisted research and drafting with a separate automated source-verification pass; no external expert or named human review is implied. ## Key facts - **Execution:** A rollup processes transactions outside L1 execution ([Scaling overview](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/index.md)) - **Validation model:** Disputes or validity proofs, depending on design ([Optimistic rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/optimistic-rollups/index.md); [Zero-knowledge rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/zk-rollups/index.md)) - **Sidechain:** An independent consensus system is not automatically a rollup ([Scaling overview](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/index.md)) ## A rollup moves execution work while retaining a settlement relationship Executing every small action directly on Ethereum is resource-intensive. A rollup executes a sequence of transactions elsewhere and publishes the information needed for its settlement model, sharing publication overhead across activity. Compression and batching can reduce per-user costs, but neither word is a security proof. The important questions are what gets published, how incorrect state can be rejected and how users can recover or exit. Evidence: [Scaling overview](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/index.md); [Data availability](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/data-availability/index.md) ## Example: a rollup receipt and Ethereum settlement are different milestones Suppose a user sends a token on a rollup and immediately sees an L2 receipt. The operator may later publish a batch to Ethereum. Its state commitment must then satisfy the rollup’s dispute or proof process. Calling every stage confirmed can hide these differences. A useful interface names the state: accepted by an operator, included in L2, data published, proof accepted or challenge conditions satisfied, and the relevant L1 finality. Evidence: [Optimistic rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/optimistic-rollups/index.md); [Zero-knowledge rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/zk-rollups/index.md) ## The same address display does not combine all balances An EVM-style address can appear on several networks, but those networks keep separate state. A balance on one does not automatically become spendable on another because the address text matches. Moving an asset across networks requires a supported mechanism such as a bridge or a service transfer. Token identity, custody and withdrawal assumptions must be checked for that route, rather than inferred from a familiar symbol. Evidence: [Scaling overview](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/index.md); [Ethereum accounts](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/accounts/index.md) ## Assess the deployed system, not only its category name Rollups can differ in who sequences activity, who may submit proofs or challenges, who holds upgrade powers and what happens during an outage. Those details determine whether theoretical protections are usable in practice. A sidechain has its own consensus; a validium puts data availability elsewhere. Calling every low-fee EVM network layer 2 can erase the very distinctions a learner needs to understand. Evidence: [Optimistic rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/optimistic-rollups/index.md); [Zero-knowledge rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/zk-rollups/index.md); [Scaling overview](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/index.md) ## Questions ### Are all EVM-compatible networks Ethereum layer 2s? No. Compatibility concerns execution and tooling. An independent sidechain can be EVM-compatible while relying on its own consensus rather than rollup settlement. Evidence: [Scaling overview](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/index.md) ### Does an L2 balance automatically appear on Ethereum mainnet? No. Different networks maintain different state. Asset movement requires a specific supported transfer or bridge process. Evidence: [Scaling overview](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/index.md) ### Does a quick receipt mean the withdrawal is ready? Not necessarily. Operator acceptance, proof or dispute completion, L1 finality and withdrawal processing can be distinct milestones. Evidence: [Optimistic rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/optimistic-rollups/index.md); [Zero-knowledge rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/zk-rollups/index.md) ## Claims and scope ### ethereum-layer-2-quick-answer An Ethereum layer 2 processes activity outside Ethereum’s main execution layer while using Ethereum for important security or settlement functions. Rollups publish data and state-related commitments to Ethereum and use disputes or validity proofs. Their actual guarantees also depend on their implementation, upgrade controls, data availability and exit mechanisms. Scope: {"collection":"ethereum","dataAsOf":null,"blockHeight":null} ### ethereum-layer-2-fact-execution Execution: A rollup processes transactions outside L1 execution Scope: {"collection":"ethereum","dataAsOf":null,"blockHeight":null} ### ethereum-layer-2-fact-validation-model Validation model: Disputes or validity proofs, depending on design Scope: {"collection":"ethereum","dataAsOf":null,"blockHeight":null} ### ethereum-layer-2-fact-sidechain Sidechain: An independent consensus system is not automatically a rollup Scope: {"collection":"ethereum","dataAsOf":null,"blockHeight":null} ## Sources - [Scaling overview](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/index.md) — ethereum.org contributors. Supports rollup execution/settlement roles and distinct security assumptions of sidechains and offchain data systems. Locator: Layer 2 scaling; rollups; sidechains; validium. Retrieved: 2026-10-02T14:35:47.354550+00:00. - [Optimistic rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/optimistic-rollups/index.md) — ethereum.org contributors. Supports challenge periods, dispute verification, sequencer ordering and withdrawal distinctions; concrete timings depend on the implementation. Locator: Fraud proving; censorship resistance; exiting the rollup. Retrieved: 2026-10-02T14:35:47.579696+00:00. - [Zero-knowledge rollups](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/scaling/zk-rollups/index.md) — ethereum.org contributors. Supports validity proofs and public rollup data; no claim that every withdrawal is instant or that every ZK system is private. Locator: Data availability; validity proofs; withdrawals; EVM compatibility. Retrieved: 2026-10-02T14:35:47.579728+00:00. - [Data availability](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/data-availability/index.md) — ethereum.org contributors. Supports why a hash is not sufficient to reconstruct data and why availability differs from permanent historical storage. Locator: Data availability problem; rollups; availability versus retrievability. Retrieved: 2026-10-02T14:35:47.112785+00:00. - [Ethereum accounts](https://raw.githubusercontent.com/ethereum/ethereum-org-website/dcc900ff125891da5b6c723b905a7113cf1bd864/public/content/developers/docs/accounts/index.md) — ethereum.org contributors. Supports accounts versus wallet software and account state fields. The older empty-code EOA description is qualified using EIP-7702. Locator: Account types; an account examined; a note on wallets. Retrieved: 2026-10-02T14:35:40.369782+00:00. ## Revision history - 2026-10-02: First publication after primary-source research and independent automated verification. ## Cite this entry Degrees of Satoshi editorial project. “Ethereum layer 2: execution elsewhere, settlement on Ethereum.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/ethereum-layer-2/