As of this writing, the price of Bitcoin is more than $7,000 per bitcoin. Several hours ago, the price touched close to or above $7,500 on the Bitstamp exchange. Because of these reasonably high prices, and the volatility, few common people have the easy money to purchase even one bitcoin. Because of this, names of Bitcoin fractions need to be developed and advertised, so that folks can buy Bitcoin fractions with understanding. A penny is a hundredth of a dollar. What is a hundredth part of a bitcoin called, or a thousandth? The smallest unit of a bitcoin is called a satoshi - one hundred millionth of a single bitcoin (0.00000001 BTC): https://en.bitcoin.it/wiki/Satoshi_(unit) - and is worth a tiny fraction of a penny. We need common names for the various in-between 10% incremental parts of a bitcoin, to make it easier for people to know what they are purchasing when they are obtaining only part of a bitcoin.