Nonce
A nonce is a value miners vary in a block header while searching for a hash that satisfies proof-of-work difficulty.
- Also known as
- number used once
Nonce stands for "number used once" and is a field in a block header that miners can change freely. By iterating the nonce (and other mutable fields), miners repeatedly hash the block header to find an output below the network’s current difficulty target. Finding such a hash constitutes valid proof-of-work.
Because the 32-bit nonce space can be exhausted quickly, miners also vary other fields (like extraNonce in the coinbase transaction or block timestamp within allowed drift) to expand the search space.
The nonce’s unpredictability and the difficulty target ensure that finding a valid block is probabilistic and expensive, securing the network against cheap block fabrication.
Related terms
4 linkedExplore connected entries beyond the alphabetical index.
Proof of Work (PoW)
→A consensus algorithm where computing power is used to solve complex problems, verify transactions, and create new blocks.
Block
→A batch of valid transactions added to a blockchain, linked to the previous block by a cryptographic hash.
Transaction
→A signed data message that asks a blockchain to transfer value, execute code, or update state.
Mempool
→A temporary storage space in a node for pending transactions that have not yet been included in a confirmed block.
All terms and definitions may update as the Cryptionary improves.
