A satoshi is the smallest indivisible unit of bitcoin, equal to one hundred-millionth of a single bitcoin, named after Bitcoin’s pseudonymous creator Satoshi Nakamoto. It is the base unit against which on-chain protocols such as Ordinals and Inscriptions operate, since each satoshi can be individually tracked and inscribed with arbitrary data. Fee markets, token standards such as BRC-20, and wallet accounting are all ultimately denominated in satoshis.