Also called ZK Rollups
A layer 2 scaling solution for the Ethereum blockchain that will allow the network to scale to greater levels. It will do so by moving computation and state storage off-chain.
This will allow for thousands of transactions to be batched and then sent back to the Mainnet. It is a process that Bitcoin uses with the Lightning Network.
Scaling
One of the most challenging factors concerning most blockchains is the ability to scale. If cryptocurrency is ever going to become a legitimate player in the realm, it requires the throughput of Visa or the banks. Even after converting from Proof-of-Work (PoW) to Proof-of-Stake (PoS), we see the capacity simply isn't there.
ZK rollups could provide a solution in that transaction batching helps to reduce the amount of data posted on-chain. Here we see a summary of the changes sent to the chain as opposed to the individual transactions.
Transactions are trustworthy through the use of validity proofs which provide cryptographic certainty.
In addition to scaling, ZK rollups enhance performance. There is no time delay with them since money is transferred as soon as the smart contract verifies the validity proof. The alternative provides the time for anyone to challenge the exit transaction.