Bitcoin is the king of digital currency, but it’s not unique. In fact, there are thousands of different types of digital currencies out there. Some of them were made as jokes, some made their founders millionaires, and others haven’t really taken off yet. And there are new ones that are being launched every single day. (check out our ICO listings). But here’s a quick guide to some of the ones you should know about like Litecoin, Ripple, and Peercoin.