What is a satoshi?

Each bitcoin (1 BTC) can have a fractional part of up to 8 digits so 1 bitcoin can be divided into 100 000 000 units.
Each of these bitcoin units (0.00000001 BTC) is called a satoshi. A satoshi is the smallest unit in a bitcoin.
This unit is named after Satoshi Nakamoto – the alias of the bitcoin creator.
There are also intermediate measurement units (microbitcoins, millibitcoins, bitcents). See the complete table of units below.