Bitcoin is a decentralized digital currency, without a central bank or single administrator, that can be sent from user to user on the peer-to-peer bitcoin network without the need for intermediaries. Transactions are verified by network nodes through cryptography and recorded in a public distributed ledger called a blockchain.
Bitcoin is unique in that there are a finite number of them: 21 million.
Satoshi Nakamoto, the pseudonymous person or persons who developed bitcoin, mined the first block of bitcoins ever (known as the genesis block), which had a reward of 50 bitcoins. Nakamoto is estimated to have mined one million bitcoins before disappearing in 2010, when he handed the network alert key and control of the code repository over to Gavin Andresen. Andresen later became lead developer at the Bitcoin Foundation.
 Andresen then sought to decentralize control. This left opportunity for controversy to develop over the future development path of bitcoin, in contrast to the perceived authority of Nakamoto’s contributions..