Rollup

A rollup refers to a scaling solution designed to improve the throughput, reduce costs, and increase the efficiency of transactions on a blockchain network. This process allows transactions to be executed off the main blockchain, which reduces congestion, speeds up transaction times, and lowers costs.
There are two main types: Optimistic Rollups, where transactions are assumed valid unless challenged, and Zero-Knowledge (ZK) Rollups, which use cryptographic proofs to ensure transaction validity without revealing transaction details.
Rollups maintain the security of the main chain by posting transaction data or proof back to Layer 1, ensuring that the transactions can be verified and are immutable. They play a crucial role in enhancing blockchain scalability while preserving decentralization and security.
All rollups are Layer 2 scaling solutions but not all Layer 2s are rollups.