Nonce

A nonce is a random whole number that miners in proof-of-work blockchains like Bitcoin iterate over to solve the cryptographic puzzle that allows them to add a new block and earn the block reward. A miner’s goal is to find a nonce where the SHA-256 hashed output begins with a certain number of zeroes. This allows POW networks to adjust the mining difficulty, requiring more zeros if blocks are being mined too fast.