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What is a modular blockchain?
A modular blockchain splits a blockchain's core jobs (running transactions, settling disputes, ordering transactions and keeping data available) across separate specialized layers or chains. A monolithic blockchain does all of them itself. A rollup that posts its data to another chain is the common example of the modular approach.
What it means for you
On a modular stack, your funds depend on several layers at once: the one that executes your transactions, the one that orders them and the one that keeps the data. A weakness at any layer, such as data held by a small committee, can stall or freeze withdrawals even if the others work. Check what each layer is before moving funds onto one.
How it works
The modular view names four functions. Execution is where applications live and state changes are computed. Settlement is an optional hub where execution layers verify proofs, resolve fraud disputes and bridge to each other. Consensus is agreement on transaction order. Data availability is verification that transaction data can be downloaded; rollups post their batches so anyone can check them. A monolithic chain handles all four, which keeps the design simple but limits throughput. A modular design lets each layer specialize and scale, at the cost of extra coordination and bridging between layers.
Sources: Celestia docs: The modular stack, ethereum.org: Data availability · checked 4 October 2026
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