Plasma

Plasma is an early Layer 2 scaling framework for Ethereum, proposed by Vitalik Buterin and Joseph Poon in 2017. Plasma creates "child chains" that process transactions off-chain and periodically commit their state to the main chain. While Plasma offered significant throughput improvements, it had limitations around data availability and complex exit procedures. It has largely been superseded by more practical solutions like optimistic rollups and zk-rollups.