Bitcoin is a new currency, a form of digital currency, created by a person called Satoshi Nakamoto in 2008. He created it on a software with block chain technology. In 2009 he placed this software in open source, making it decentralised. This means there is no ownership of this software. In 2009 the value of a Bitcoin was almost zero or few cents may be.
Value of Bitcoin
As Bitcoins were promoted, there were very few takers. Some bought few thousand of bitcoins but were not able to buy anything from it. Gradually the demand was created and value of Bitcoin started rising. Four years later in 2012 it was around USD 12. In the year 2015 it rose beyond USD 200. In 2016 as we write in April 2016 Value of Bitcoin is quoted at USD 450.
No currency or commodity had ever appreciated like Bitcoin did. There are several other digital currency which are no where near value of Bitcoin or market capitalisation.
Bitcoin market capitalisation today stands at over USD 7 billion. Total number of bitcoins in circulation as of April 2016 are 15.47 million.