Bitcoin is a decentralised, Open-source payment system made possible by decades of innovation in computer science. With Bitcoin, users can send money directly to one another, without the use of a third party and with fees totalling less than a few cents - all over the world.
As digital currency, Bitcoin don't physically exist – they are actually numeric codes secured by layers of cryptography and stored on your computer. Each individual Bitcoin is divisible into 100,000,000 individual increments, called Satoshis. As of 2015, there are over 14 million Bitcoin in circulation. Only 21 million will ever be mined.
Bitcoin's intangibility is perhaps best compared to the credit or debit card data you provide to online merchants when making purchases over the Internet. Just as with the money on your card, you don't physically hold the cash. Unlike credit cards, there is no bank to deal with, no plastic to keep, and it can't be stolen just by somebody knowing the numbers on your card.