Layer-2 networks and rollups, simply

A busy blockchain can only process so many transactions in each block, and when demand rises, confirmations slow down. A layer-2 network is a separate chain that runs alongside a main chain, called layer 1, to take some of that work. The most common design is the rollup. A rollup carries out transactions on its own, bundles many of them into one batch and posts a compressed record of that batch to the main chain. The main chain therefore stores the evidence without repeating every step. Think of a shop assistant who tallies a day's receipts and hands the accountant one summary sheet, with the receipts kept available in case someone asks to check them.

Rollups differ in how the main chain learns that a batch is correct. An optimistic rollup assumes the batch is valid and leaves a period in which any observer may submit a fraud proof if something is wrong; a dishonest party can lose a posted bond. A validity rollup attaches a mathematical proof that the batch was computed properly. Both designs add trust assumptions: a few operators often order transactions, code upgrades may be controlled by a small group, and moving assets back to the main chain can take days while a challenge period runs. Bridges connecting the layers add further risk. Learn who runs the sequencer, who can upgrade the contracts and how exits work.