Proof of Work (PoW)

Proof of Work is how Zcash — like Bitcoin — decides who gets to add the next block to the blockchain and secures its transaction history. Miners compete to solve a computationally hard puzzle; whoever finds a valid solution first proposes the next block and earns the block reward. Rewriting past transactions would require out-computing the entire honest network, which gets harder as more mining power joins it.

Zcash's specific Proof-of-Work algorithm is Equihash. Proof of Work itself doesn't reveal anything about the contents of shielded transactions — mining and privacy are separate systems within the same protocol.