What Are Ethereum Rollups and How Do They Reduce Transaction Fees?

Ethereum has a capacity problem that becomes easier to see when the network is busy: every transaction competing for space on the main chain adds pressure to a system where block space is limited.That creates an obvious question. If Ethereum is not going to process every transaction directly on its mainnet, where does the work happen — and how can the network still know that the result is correct?That is the basic idea behind Ethereum rollups. They move much of the transaction execution to