Bitpay is a leading bitcoin payment processor that does a lot and is behind the recent story about Ohio accepting bitcoins for taxes and now overstock is going to pay their taxes in bitcoin
Bitcoin is the reserve currency of the crypto-market and serves a similar purpose as USD does in FX markets
It's also the base layer for other networks to work on top of to perform a variety of functions like securing data records
People also use it for black markets and money laundering, ransomware etc. lol, but that's kind of dumb because it's a public ledger which is how the corrupt FBI agents got caught in the Ross Ulbrict case which you should check out the doc on him the Silk Road dark net market was big in the early days and hardcore bitcoiners still shill for him to get freed from prison
It's internet money so it's used all over the place for accepting donations and stuff easily, it's a global phenomenon