Bitcoin comes into the world through a process called mining. It’s an analogy to gold mining, but instead of actual mining, new Bitcoins are created using computer power. In the past it would have been worthwhile to mine Bitcoin.
Today such huge computer power is required that bitcoin mining is not usually profitable. Currently, there are total of 16.5 million Bitcoins, and the mining process will continue until reaching the maximum limit of 21 million Bitcoins