Rollups are a type of technology used in blockchain networks to improve scalability and transaction speed. They work by bundling multiple transactions together into a single batch, which is then processed on the main blockchain. This reduces the load on the main network and allows for faster and cheaper transactions. There are different types of rollups, including Optimistic Rollups and ZK-Rollups. Optimistic Rollups assume transactions are valid and only check them if there is a dispute, while ZK-Rollups use cryptographic proofs to verify transactions without revealing the details. Both methods aim to enhance the efficiency of blockchain systems.