Bitcoin (BTC, XBT) is the first (virtual, digital) cryptocurrency introduced in 2009 as an open source project by a unknown named Satoshi Nakamoto. Bitcoin prices have changed a lot since then: nearly $ 20,000 in December 2017. Bitcoin
remains the most valuable, highest capped value of all cryptocurrencies. Since 2009 there have been many hardforks from Bitcoin, like Litecoin or Bitcoin Cash.
Because it's an open source project, anyone can use it and generate Bitcoin. Now it is very expensive and difficult: Bitcoin Mining needs very good hardware and a lot of power. But you can easily buy Bitcoin, at exchanges like Coinbase, Kraken, Bitfinex, ...
Online bookmakers - sports betting sites with Bitcoin as payment option: 1xBet • 22Bet