Execution Layer

The execution layer is the part of a blockchain stack that actually runs transactions and smart contracts and computes the resulting state — account balances, contract storage and everything else the network tracks. On Ethereum, the execution layer processes transactions in the Ethereum Virtual Machine while a separate consensus layer decides which blocks are canonical. In modular designs a rollup serves as the execution layer, batching user transactions and posting the results down to a settlement or data layer. Execution is normally the most resource-hungry job in the stack, which is why most scaling work targets it. Users feel this layer directly: it determines gas costs, how fast a transaction confirms, and which contract languages and tools are supported.