Ethereum Layer 2 Optimistic Rollups & ZK-Rollups (Zero Knowledge Rollups)
Since gas fees on Ethereum mainnet can get to the hundreds of dollars during high txn season, there have been Ethereum Layer 2 projects attempting to solve this scalability issue.
Optimistic Rollups and ZK-Rollups are types of Ethereum Layer 2 scaling solution to handle more transactions and reduce gas fees.
Main differences
1. Optimistic Rollups transactions are assumed to be valid until it is proven otherwise
2. ZK-Rollups transactions are invalid until proven valid.
Both types of rollups have their own use cases and benefits. Here is the list of some projects using the Optimistic Rollups and ZK-Rollups: