Plasma is an early Layer-2 scaling design for Ethereum that uses child chains and fraud proofs to offload most transaction processing from the main chain. Instead of executing every transaction on Ethereum mainnet, Plasma chains bundle many transactions together and periodically commit a summary of their state back to Ethereum.
Users can exit a Plasma chain back to the main chain if an operator behaves maliciously by using fraud proofs to challenge invalid state updates. While Plasma helped pioneer off-chain scaling ideas, it has largely been superseded in practice by newer approaches such as rollups, which publish more data on-chain and support more general smart-contract execution.
