Bitcoin is one of SHA-256-based Cryptocurrencies, (find Secret How To Earn More Than 10,000 Satoshi Every Hour at http://vocems.dipopedia.com/2015/10/18-secret-how-to-earn-more-than-10000-satoshi-every-hour.html) a payment system invented by Satoshi Nakamoto. The system is peer-to-peer; users can transact directly without needing an intermediary. The system works without a central repository or single administrator, which has led the US Treasury to categorize it as a decentralized virtual currency.
Bitcoin was the first practical implementation and is currently the most prominent triple entry bookkeeping system in existence. Everyone has access to all of the source code all of the time and any developer can review or modify the software code. As such, the identity of Bitcoin's inventor is probably as relevant today as the identity of the person who invented paper. Nobody owns the Bitcoin network much like no one owns the technology behind email or the Internet.
Behind the scenes, the Bitcoin network is sharing a massive public ledger called the "block chain". Supply growth of Bitcoin is 25 bitcoins per block (approximately every ten minutes) until mid 2016, and then afterwards 12.5 bitcoins per block for 4 years until next halving. This halving continues until 2110-2140 when 21 million bitcoins have been issued.
The unit of account of the bitcoin system is bitcoin. As of 2014, symbols used to represent bitcoin are BTC, XBT, and BitcoinSign.svg. Small amounts of bitcoin used as alternative units are millibitcoin (mBTC), microbitcoin (µBTC), and satoshi. Named in homage to bitcoin's creator, a satoshi is the smallest amount within bitcoin representing 0.00000001 bitcoin, one hundred millionth of a bitcoin. A millibitcoin equals to 0.001 bitcoin, which is one thousandth of bitcoin. One microbitcoin equals to 0.000001 bitcoin, which is one millionth of bitcoin. A microbitcoin is sometimes referred to as a bit. On 7 October 2014, the Bitcoin Foundation disseminated a plan to apply for an ISO 4217 currency code for bitcoin, and mentioned BTC and XBT as the leading candidates.
Value forecasts of Bitcoin are financial journalists and analysts, economists, and investors have attempted to predict the possible future value of bitcoin. In April 2013, economist John Quiggin stated, "bitcoins will attain their true value of zero sooner or later, but it is impossible to say when". A similar forecast was made in November 2014 by economist Kevin Dowd. In November 2014, David Yermack, Professor of Finance at New York University Stern School of Business, forecast that in November 2015 bitcoin may be all but worthless. In December 2013, teacher Mark T. Williams forecast a bitcoin would be worth less than $10 by July 2014. In the indicated period bitcoin has exchanged as low as $344 (April 2014) and during July 2014 the bitcoin low was $609. In December 2014, Mr Williams said, "The probability of success is low, but if it does hit, the reward will be very large."In May 2013, Bank of America FX and Rate Strategist David Woo forecast a maximum fair value per bitcoin of $1,300. Bitcoin investor Cameron Winklevoss stated in December 2013 that the "small bull case scenario for bitcoin is... 40,000 USD a coin".