When discussing Ethereum's scalability issues, the concept of Plasma must be mentioned. Early on, Joseph Poon and Vitalik Buterin proposed this solution. The core idea is quite simple: build a layered "child chain" architecture to process transactions, periodically submitting only the final results to the main chain. This approach significantly reduces the pressure on the mainnet, greatly improves transaction speed, and lowers transaction fees accordingly. From a technical design perspective, Plasma chains have their own consensus mechanisms and block production logic, with security guaranteed by the main chain’s final arbitration. However, in practice, Plasma has encountered many challenges, especially technical issues like data availability, which has led it to be more of a theoretical concept in discussions. Although there are not many direct successful applications, the design philosophy of Plasma has had a profound influence. Later Layer 2 solutions like Rollup evolved from this foundation.