Definition
A rollup is a blockchain scalability concept in which a large number of transactions are executed off the base layer and then aggregated into a single, compact representation that is recorded on the main chain. Instead of every transaction being processed and stored directly on the base layer, the rollup posts batched data and cryptographic commitments to the underlying blockchain. This design preserves the security guarantees of the base chain while significantly increasing effective throughput and reducing per-transaction data on-chain.
Rollups rely on a separation between execution and data availability, with transaction computation occurring off-chain and minimal, compressed data being stored on-chain. Different rollup designs use distinct mechanisms to prove correctness of state transitions, but they all share the core idea of outsourcing execution while anchoring finality and security to the base layer. In ecosystems where networks like Polygon or other Layer 2 environments operate, rollups are a central concept for scaling without creating entirely separate security assumptions.
Context and Usage
In technical discussions, the term rollup typically refers to a Layer 2 construction that inherits security from a Layer 1 chain by regularly posting transaction data and state roots on-chain. The rollup environment maintains its own state and execution logic, but its canonical history is ultimately derived from the data and commitments published to the base layer. This makes rollups distinct from sidechains, which maintain more independent security models.
Within broader scaling architectures that may include solutions such as Polygon or other Layer 2 frameworks, rollups are treated as a primary method for increasing capacity while keeping settlement and dispute resolution anchored to a highly secure base chain. The concept is used to categorize protocols and designs that follow this aggregate-and-commit pattern, regardless of the specific proving system or virtual machine they implement. As a result, “rollup” functions as a foundational term in advanced discussions of modular and multi-layer blockchain ecosystems.