At present, blockchains face scalability issues. Although decentralized and transparent, they suffer from slow transaction speeds and high costs. There are three scalability solutions:1,Optimizing blockchain protocols for each node (like DAG, Hashgraph, Avalanche).2,Sharding (still immature).3,Moving most transactions off-chain via Layer-2 solutions.Public chains remain the most effective way to achieve global consensus but are also the slowest databases. Therefore, blockchains should focus on decentralization and security, while scalability and privacy issues can be addressed by off-chain solutions. Adding a new layer on top of the blockchain, using it as a security anchor. Existing solutions include some for payment scaling, some for smart contract scaling, and some for off-chain computation.