zk-SNARK

Succinct Non-interactive ARgument of Knowledge — the original zero-knowledge proof family used in production crypto. Small proofs (~200-500 bytes), fast verification, but historically required trusted setup ceremonies. Zcash pioneered production zk-SNARKs in 2016. Used by many ZK rollups (Polygon zkEVM, Aztec) and privacy chains. Halo 2 variants eliminated the trusted setup requirement.