Satoshi
A satoshi is the smallest divisible unit of bitcoin. One bitcoin equals 100 million satoshis, so a satoshi is 0.00000001 BTC.
How it works
Because a whole bitcoin can represent a large amount of value, satoshis allow very small and precise amounts to be sent and priced. The unit is named after Satoshi Nakamoto, Bitcoin’s pseudonymous creator. Other cryptocurrencies have their own smallest units defined by how many decimal places their protocol allows. Layer-2 systems such as the Lightning Network operate in satoshis (and even smaller units) to enable tiny, low-cost payments.
Why it matters
Satoshis make bitcoin practical for small transactions and fine-grained pricing without needing to deal in fractions of a whole coin. As interest in small denominations has grown, prices are increasingly quoted in “sats.”
Example
Sending 50,000 satoshis is the same as sending 0.0005 bitcoin, just expressed in the network’s smallest unit.