What is zk-rollups?

A zero-knowledge rollup is a Layer 2 blockchain solution that performs computations and storage off-chain while funds are held in a smart contract.

Simply put, zero-knowledge rollups or zk-rollups is a layer-2 scalability solution that allows blockchains to validate transactions faster while also ensuring that gas fees remain minimal. Zk-rollups manage to perform better than traditional layer-1 blockchains because they combine on and off-chain processes.

While the Ethereum mainnet explicitly utilizes on-chain activities to process transactions and validate blocks, layer-2 zk-rollup solutions introduce off-chain functionalities as well. One of the main components that allow them to successfully validate transactions faster than layer-1 blockchains are Merkle Trees.

Merkle Tree is an important mathematical structure that allows blockchains to ensure that no one can fake data on the on-chain records of a zk-rollup. Usually, a zk-rollup consists of two Merkle Trees which are both stored on a smart contract, or in other words, on-chain. One tree is dedicated to storing accounts, while the other stores all balances. Any other type of data generated and used by the zk-rollup is stored off-chain.

Zk-rollups are becoming increasingly popular both among developers who are looking to boost usability and among investors and traders looking for faster and cheaper transaction processing.