Bitcoin Cash is a fork of Bitcoin that increased the block size to enable more transactions per second and lower fees. It emerged from the 2017 scaling debate and positions itself as the original vision of Bitcoin as peer-to-peer electronic cash.
Layer 2 (L2) is a collective term for off-chain scaling solutions that inherit the security of a Layer 1 blockchain while processing transactions faster and cheaper. Major categories include Optimistic Rollups (Arbitrum, Optimism) and ZK Rollups (StarkNet, zkSync).
Zero-knowledge proofs (ZKPs) are cryptographic methods that allow one party to prove they know something without revealing what that thing is. In blockchain, they enable both privacy and scaling — proving off-chain computation is correct without re-executing it on-chain.