Source
Bitcoin is a cryptocurrency and worldwide payment system. It is initial decentralized digital currency. The system works without a central bank or single administrator.The network is transacting together together amid users directly, without an agent. These transactions are establishing by network nodes through the use of cryptography.It is aslo recorded in a public distributed ledger called a blockchain. Bitcoin was invented by an unspecified person or group of people. Bitcoins are created as a reward for a process known as mining. They can be exchanged for supplementary currencies, products, and facilities. As of February 2015, on pinnacle of 100,000 merchants and vendors accepted bitcoin as payment. In 2017, there are 2.9 to 5.8 million unique users using a cryptocurrency wallet, most of them using bitcoin.
Source
Source