Optimistic Rollup is a layer 2 scalability solution designed to improve transaction speed and reduce costs on blockchains. It operates by processing transactions off-chain while still relying on the security of the main blockchain.In an Optimistic Rollup, transactions are grouped together and processed in batches. These batches are submitted to the main chain where they are assumed to be valid by default. This “optimistic” approach allows for faster processing since it doesn’t require immediate validation of every transaction.To secure the system, there is a challenge mechanism. If a participant believes a batch contains fraudulent transactions, they can submit a challenge. The main chain then verifies the disputed transactions, and if any fraud is detected, the dishonest party faces penalties.This design strikes a balance between speed and security, enabling high throughput while still being anchored to the main blockchain for trust and finality. As a result, Optimistic Rollups are gaining popularity for applications that demand quick and cost-effective transactions.