What Is ?
Bitcoin is the first digitally native money, un like your online checking account, which is just a digital form of central bank fiat.
Bitcoin is decentralized digital currency.
Bitcoin has no central authority.
Bitcoin is stateless.
Consider the implications ...
Bitcoin is a decentralized digital currency that enables instant payments to anyone, anywhere in the world. Bitcoin uses peer-to-peer technology to operate with no central authority: transaction management and money issuance are carried out collectively by the network.
~ Bitcoin Wiki
en.bitcoin.it