A Layer 2 scaling solution that bundles (rolls up) multiple transactions into a single batch that is processed off-chain and submitted to the main blockchain.
Detailed Explanation
Rollups dramatically increase blockchain throughput by executing transactions on a separate layer and posting compressed data back to Layer 1 for security. There are two main types: Optimistic Rollups (like Arbitrum and Optimism) assume transactions are valid unless challenged within a dispute period, while ZK-Rollups (like zkSync and StarkNet) use zero-knowledge proofs to cryptographically verify transaction validity. Both approaches inherit the security of the underlying Layer 1 blockchain.
Why It Matters
Rollups are considered the primary scaling strategy for Ethereum, capable of increasing throughput from roughly 15 transactions per second to thousands while maintaining security. They reduce gas costs by 10-100x for users, making DeFi and NFT transactions affordable. The rollup-centric roadmap is central to Ethereum's long-term vision of becoming a global settlement layer.
Key Considerations
When choosing a rollup, consider transaction costs, finality time, ecosystem maturity, and bridge security. Optimistic rollups have a 7-day withdrawal period to mainnet, while ZK rollups offer faster finality. The rollup ecosystem is rapidly evolving with increasing competition driving costs down and features up.
Example
When using Arbitrum (an Optimistic Rollup), a user can swap tokens on Uniswap for a fraction of Ethereum mainnet costs. Arbitrum batches hundreds of such swaps together, compresses the data, and submits a single proof to Ethereum, drastically reducing per-transaction costs.
Related Terms
Frequently Asked Questions
A Layer 2 scaling solution that bundles (rolls up) multiple transactions into a single batch that is processed off-chain and submitted to the main blockchain.
Rollups are considered the primary scaling strategy for Ethereum, capable of increasing throughput from roughly 15 transactions per second to thousands while maintaining security.
Optimistic rollups assume transactions are valid unless challenged within a dispute period (7 days). ZK rollups use cryptographic proofs to verify validity immediately. ZK rollups offer faster finality but are more complex to build. Both inherit Ethereum's security guarantees.