Plasma
An early Ethereum scaling framework using child chains that periodically commit data roots to the mainchain and rely on fraud proofs for security, largely superseded by rollups.
Plasma was one of the earliest proposed frameworks for scaling Ethereum, built around "child chains" that process transactions independently and periodically submit a compact cryptographic commitment (a Merkle root, see Kaavon's "Merkle Tree" glossary definition) of their state back to the Ethereum mainchain. Security relied on fraud proofs (see Kaavon's "Fraud Proof" glossary definition): if a child chain operator tried to cheat, any user could submit evidence of the fraud to the mainchain and force a correction, with a built-in exit mechanism letting users withdraw funds directly from the mainchain if they believed the child chain was compromised.
Plasma's practical adoption was limited by difficulties handling complex smart contract state and by the complexity of its exit and challenge mechanisms for ordinary users, and it was largely superseded by rollups (see Kaavon's dedicated Layer 2 guides), which post transaction data directly to the base layer and so avoid Plasma's hardest problems around data availability and mass user exits. Plasma remains historically significant as an important conceptual precursor to today's rollup-centric scaling roadmap.
Examples
- Plasma's fraud-proof and exit-game design directly influenced the security model later used by optimistic rollups.
- Few Plasma implementations saw significant production use before the ecosystem shifted toward rollups as the dominant Layer 2 scaling approach.