Rollup
A Layer 2 scaling solution that bundles many transactions together and submits them to the main chain as a single batch.
Rollups are the most popular type of Layer 2 technology. They "roll up" hundreds of transactions into a compressed batch and post it to Ethereum. This spreads the cost of Ethereum's security across many transactions, making each one much cheaper.
There are two main types. Optimistic rollups (used by Base, Arbitrum, Optimism) assume transactions are valid unless challenged. Zero-knowledge rollups (used by zkSync, Starknet) use mathematical proofs to verify validity. Both achieve the same goal: cheaper transactions with Ethereum-level security.
Base, where much of USDC activity happens, is an optimistic rollup built by Coinbase. It's one of the cheapest ways to use USDC.
Related Terms
Layer 2 (L2)
A secondary network built on top of a Layer 1 blockchain to increase speed and reduce transaction costs. Examples: Base, Arbitrum, Optimism.
Layer 1 (L1)
The base blockchain network that processes and finalizes transactions on its own. Examples: Ethereum, Solana, Avalanche.
Gas Fees
Transaction fees paid to blockchain validators for processing and confirming transactions.
Blockchain
A distributed, immutable digital ledger that records transactions across a network of computers.
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This definition is provided for educational purposes. USDC.org is an independent resource and is not affiliated with Circle Internet Financial.