What is BitCoin?
Since anything digital can be copied over and over again, the hard part about implementing a digital payment system is making sure that nobody spends the same money more than once. Traditionally, this is done by having a trusted central authority (like PayPal) that verifies all of the transactions. The core innovation that makes Bitcoin special is that it uses consensus in a massive peer-to-peer network to verify transactions. This results in a system where payments are non-reversible, accounts cannot be frozen, and transaction fees are much lower.
Introduction To BitCoin
The BitCoin Foundation
Bitcoin Foundation standardizes, protects and promotes the use of Bitcoin cryptographic money for the benefit of users worldwide.
 The Bitcoin Foundation Website.