Unlike the physical versions of global currencies, such as the British pound or U.S. dollar, cryptocurrencies predominately exist in the digital world. Despite this difference, a cryptocurrency can be divided into smaller units, just as the pound is broken into pence and the dollar into cents. In the case of bitcoins, the smallest unit available is called the satoshi.
The satoshi unit is named after Satoshi Nakamoto, published a paper in 2008 that jumpstarted the development of the bitcoin cryptocurrency. The paper, “Bitcoin: A Peer-to-Peer Electronic Cash System”, described the use of a peer-to-peer network as a solution to the problem of double-spending. The problem – that a digital currency or token can used in more than one transaction – is not found in physical currencies, as a physical bill or coin can, by its nature, only exist in one place at a single time. Since a digital currency does not exist in the physical space, using it in a transaction does not remove it from someone’s possession.