50 terms
Glossary
There are a lot of new words here, and that is fine. The common ones are explained below in plain language, each with what it looks like in this city.
L1L2RollupOptimistic rollupFraud proofZK rollupValidity proofzkEVMSidechainData availabilityOptimiumBlobGasgweiBase feeTPSBlockBeacon chainProof of stakeFinalitySequencerBased rollupRollup stageBridgeTVLMarket capTokenStablecoinGas tokenGovernance tokenStakingDeFiDEXRWAMemecoinWrapped assetWalletENSSignatureSmart contractEVMRPCBlock explorerSuperchainArbitrum NitroAgglayerUpgradesMEVWhaleAll-time high
- L1 (Layer 1)
- The base blockchain that finally settles transactions and keeps the record. Ethereum mainnet is the L1.
- In the city: Downtown, in the middle.
- L2 (Layer 2)
- A chain that processes transactions separately on top of L1 and posts only the results and data to L1. It borrows L1’s security while charging far lower fees.
- In the city: The districts around downtown.
- Rollup
- A kind of L2 that bundles (“rolls up”) many transactions and posts their data and a summary to L1. Because the data is on L1, anyone can recompute the L2’s state.
- In the city: A district that sends container trucks downtown is a rollup.
- Optimistic rollup
- A rollup that assumes posted results are correct and finalises them unless someone proves otherwise within a challenge period, usually seven days.
- In the city: The Superchain quarter in the west and the Arbitrum quarter in the east work this way.
- Fraud proof (fault proof)
- The procedure by which someone proves to L1 that an optimistic rollup’s posted result is wrong. If anyone may submit one, it is called permissionless.
- ZK rollup
- A rollup that posts a mathematical proof (a validity proof) that its batch was computed correctly, which L1 verifies directly. There is no challenge period to wait for.
- In the city: The purple quarter in the north.
- Validity proof (zero-knowledge proof)
- Cryptography that proves a computation was done correctly, briefly and without revealing all of it. SNARKs and STARKs are the main families.
- zkEVM
- A system that can prove, with zero-knowledge proofs, programs written for Ethereum’s execution environment (the EVM) with little or no change.
- Sidechain
- An independent chain secured by its own validators rather than by Ethereum. Assets move between it and Ethereum only through bridges.
- In the city: The satellite towns across the river to the south.
- Data availability (DA)
- Whether transaction data is published so that anyone can download it. Without the data, nobody can verify the chain’s state or withdraw assets.
- Optimium · Validium
- Chains that work like rollups but keep their data outside L1 (on EigenDA, with a committee, and so on). Cheaper, but they require trusting that outside party.
- In the city: Celo, Fraxtal and MegaETH are built this way.
- Blob
- Temporary data space added to L1 in March 2024 (EIP-4844) so that L2s can post data cheaply. Blobs are deleted after about 18 days.
- In the city: The container trucks driving from a district to the blob depot downtown.
- Gas
- The unit of computation a transaction uses, and the fee paid for it. More complex transactions use more gas.
- In the city: The colour of the downtown ring road is the current gas price.
- gwei
- The unit gas prices are quoted in. One gwei is a billionth of an ETH.
- Base fee
- The minimum gas price, which rises when blocks are full and falls when they are not (EIP-1559). This part is burned rather than paid to anyone.
- TPS
- Transactions per second: how much a chain is being used right now.
- In the city: The number and kind of vehicles on a district’s roads.
- Block · Slot
- A block is one batch of transactions. On Ethereum a turn to produce a block (a slot) comes every 12 seconds.
- In the city: A flash of the lighthouse and a ripple across a district mean a new block.
- Beacon chain
- The layer of Ethereum that runs consensus: who proposes and who attests to the next block.
- In the city: The lighthouse downtown.
- Proof of stake · Validator
- The consensus method in which participants who have staked ETH propose and attest to blocks. Breaking the rules costs them part of their stake.
- Finality
- The point at which a transaction can no longer be reversed. On Ethereum this normally takes about 13 minutes.
- Sequencer
- The operator that orders transactions and builds blocks on an L2. Today most L2s run a single sequencer themselves.
- Based rollup
- A rollup with no separate sequencer: Ethereum’s own block proposers also order the L2’s blocks.
- In the city: Taiko Alethia works this way.
- Rollup stage (Stage 0, 1, 2)
- L2BEAT’s rating of how little you have to trust a rollup’s operators. The higher the number, the less they can do on their own.
- In the city: The stage is shown in district panels and on district pages.
- Bridge
- A mechanism for moving assets between chains. Usually you lock an asset on one side and receive the same amount on the other.
- In the city: Buses leaving downtown for a district are bridge deposits.
- TVL (total value locked)
- The total value of assets deposited on a chain or in a service.
- In the city: How wide and dense a district is.
- Market cap
- A token’s price multiplied by its circulating supply.
- In the city: The height of the buildings.
- Token · ERC-20
- An asset issued on a chain. ERC-20 is the name of the common standard tokens follow on Ethereum.
- In the city: The shops under the buildings are tokens.
- Stablecoin
- A token designed to hold the value of a currency such as the dollar (USDC, USDT, DAI and others).
- In the city: The banks and exchange counters with the 🏦 sign.
- Gas token
- The asset fees are paid in on a chain. Most L2s use ETH; some chains use their own token (MNT, CELO, FRAX, POL, xDAI).
- In the city: The gas stations with the ⛽ sign.
- Governance token
- A token used to vote on changes to a chain’s or a service’s rules.
- In the city: The district office with the 🏛 sign.
- Staking · LST
- Staking means committing ETH to validation and earning rewards. An LST (liquid staking token) is a receipt-like token you get in return and can use freely (stETH and others).
- In the city: The power plants with the ⚡ sign.
- DeFi
- Finance — swapping, lending and so on — run by programs (smart contracts) rather than by intermediaries such as banks.
- In the city: The markets with the 🛒 sign.
- DEX (decentralised exchange)
- An exchange where a program, not a company, swaps tokens (Uniswap, for example).
- RWA (real-world assets)
- Real-world assets such as treasury bills, stocks or property represented as tokens.
- In the city: The offices with the 🏢 sign.
- Memecoin
- A token whose price is driven by trends and community rather than by use. Extremely volatile.
- In the city: The shops with the 🎪 sign.
- Wrapped asset
- A token that represents an asset from elsewhere (bitcoin, for example) at the same value so it can be used on this chain (WBTC, WETH).
- In the city: The shops with the 🛂 sign.
- Wallet · Address
- A wallet manages assets with a private key; an address, starting with 0x, is where assets are received. Never share a private key or recovery phrase with anyone.
- In the city: Enter an address and a house appears near the chain that wallet uses most.
- ENS
- A name, such as name.eth, used in place of a long 0x address.
- In the city: You can search by ENS name to find a house.
- Signature
- Proving with your private key that a request really comes from you. A signature that is not a transaction costs no fee and moves no assets.
- In the city: A citizen signs once to verify a wallet.
- Smart contract
- A program stored on a blockchain that runs by itself according to fixed rules.
- EVM
- The virtual computer that runs smart contracts on Ethereum. Most L2s use the same EVM, so programs can be moved over unchanged.
- RPC
- The interface for asking a blockchain questions such as “what is the latest block?”
- In the city: The city asks each chain’s public RPC directly for live numbers.
- Block explorer
- A site where you can look up blocks, transactions and addresses (Etherscan, for example).
- In the city: Each district page links to its explorer.
- Superchain · OP Stack
- The OP Stack is Optimism’s toolkit for building L2s; the Superchain is the group of chains built with it that share standards and upgrades.
- In the city: The quarter west of downtown.
- Arbitrum Nitro · Orbit
- Nitro is Arbitrum’s execution technology; Orbit is the framework that lets anyone launch their own chain with it.
- In the city: The quarter east of downtown.
- Agglayer
- Polygon’s connection layer for joining the assets and messages of many chains.
- In the city: Katana is connected through the Agglayer.
- Upgrades (Dencun, Pectra, Fusaka)
- Ethereum changes its rules roughly once a year or two. Dencun (March 2024) introduced blobs, Pectra (May 2025) expanded wallet features and blob capacity, and Fusaka (December 2025) made room for many more blobs.
- MEV
- The profit available to whoever orders the transactions in a block, by choosing that order.
- Whale
- A nickname for an address that moves very large amounts.
- In the city: Gold cash vans and helicopters are whale moves.
- All-time high (ATH)
- The highest price so far.
- In the city: Fireworks go up over a shop when its token surges.
Facts on this page are as of 2026-10 and may change. If you spot a mistake, please tell us through the contact page.