A single bitcoin, like a dollar, is divisible, and the smallest unit is known as a satoshi. The satoshi is not bitcoin's only subdivision. A millibitcoin is one-thousandth of a bitcoin (0.001 BTC). A microbitcoin, or 0.000001 BTC, is one-millionth of a bitcoin. It is possible to transact on the Lightning network using a unit even smaller than the satoshi. The millisatoshi is one-thousandth the size of a single satoshi, but it is not usable on the bitcoin network itself.

A satoshi is the smallest unit of Bitcoin, named after Bitcoin's pseudonymous creator, Satoshi Nakamoto. One satoshi represents 0.00000001 BTC (Bitcoin), meaning it takes 100 million satoshis to equal one Bitcoin. This tiny unit allows for microtransactions, making Bitcoin versatile for both small and large payments. The use of satoshis is significant because as Bitcoin's value increases, smaller units are needed for everyday transactions. The concept emphasizes Bitcoin's divisibility, a key feature that supports its use as a digital currency. Satoshis are crucial in making Bitcoin accessible to a broader audience, allowing users to own and transact with fractions of a Bitcoin, rather than needing to own or trade whole Bitcoins.