zk-Rollup

A zk-Rollup is a Layer 2 scaling solution that executes transactions off-chain and submits succinct cryptographic proofs (usually zk-SNARKs or zk-STARKs) to the main blockchain, boosting scalability and lowering costs while maintaining Layer 1-level security.

zk-Rollups bundle hundreds or thousands of transactions into a single batch, execute them off-chain, generate a validity proof confirming all transactions comply with protocol rules, and post the proof plus minimal transaction data to the main blockchain. The Layer 1 chain verifies the compact proof rather than re-executing individual transactions, enabling throughput increases of 10-100x while inheriting the security guarantees of the underlying blockchain.

Unlike optimistic rollups which assume transactions are valid and rely on fraud proofs with challenge periods, zk-rollups provide instant finality since every batch's validity proof mathematically guarantees correctness before acceptance. This eliminates withdrawal delays and reduces capital efficiency costs. Major zk-rollup implementations include zkSync, StarkNet, Polygon zkEVM, and Scroll, with growing adoption for DeFi applications, NFT platforms, and payment systems requiring high throughput with strong security and fast settlement.