layer2-scaling

A <a href="/en/glossary/layer2-scaling/rollup/">Rollup</a> is a <a href="https://crypto-bible.com/en/glossary/blockchain-fundamentals/layer-2/" target="_blank" rel="noopener">Layer 2</a> scaling technology that executes large volumes of transactions off the main chain, posting back only compressed results and verification data — giving users far lower fees than the main chain while still inheriting its security guarantees.

A <a href="/en/glossary/layer2-scaling/sequencer/">Sequencer</a> is the component on a <a href="/en/glossary/layer2-scaling/rollup/">Rollup</a> responsible for receiving user transactions, deciding the order they execute in, and providing instant soft confirmations. The vast majority of major rollups still run their sequencer under a single operator, making it the primary — and most closely watched — source of centralization risk in the <a href="https://crypto-bible.com/en/glossary/blockchain-fundamentals/layer-2/" target="_blank" rel="noopener">rollup</a> architecture.

Sharding splits a blockchain's data processing or verification workload into multiple parallel parts so different nodes each handle a portion, breaking through the fundamental bottleneck of requiring every node to process all data.