Bitcoin is an online cash currency launched in early 2009. Bitcoin was formed to be a form of electronic cash that could be sent peer-to-peer without the need for a central bank or other authority to operate and maintain the ledger, much as how physical cash is used.
The engine or machine that turns the bitcoin ledger is original and largest block-chain, while other block-chains turns nearly hundred other alike currency projects by different rules.
Bitcoin works by paying miners to those that do the computational legwork of posting new transactions – with newly-minted bitcoins. As long as the currency is desirable, it is self-sustaining. The system automatically adjusts the difficulty of posting transactions and the reward for doing so to control inflation.