Bitcoin was the first Crypto or Cryptocurrency. and is still the biggest. All of them have the same basic underpinnings: they use a "blockchain", a shared public record of transactions..to create and track a new type of digital token one that can only be made and shared according to the agreed-upon rules of the network, whatever they may be. but the flourishing ecosystem has proven a huge amount of variation on top of that. some cryptocurrencies, such us Litecoin or Dogecoin, fulfill the same purpose as bitcoin -building a new digital currency- with tweaks to some of the details (making transactions faster, for instance, or ensuring a basic level of inflation). And whether this is the end of 'real' money.