A satoshi is the smallest unit of Bitcoin. Each BTC can be separated into 100 million satoshis - in other words, a satoshi is equal to 0.00000001 BTC. The name "satoshi" is derived from "Satoshi Nakamoto", which is the pseudonym used by the inventor of Bitcoin. When talking about satoshis, users commonly use the abbreviation "sats".
Referring to prices in terms of satoshis can be useful when dealing with smaller amounts. For example, instead of saying that you sent 0.00049 BTC to youir friend, you can simply say that you sent them 49,000 satoshis. In order to convert from BTC to satoshis, you have to multiply the BTC amount by 100,000,000.
Please note that satoshi is not a separate cryptocurrency, and just refers to the smallest unit of Bitcoin. Some users prefer to use satoshis instead of BTC for pricing purposes, so we added a satoshi listing to CoinCodex as a convenience. Referring to prices in satoshis is becoming more intuitive as the Bitcoin price grows higher.