A controversial cryptocurrency that is not decentralized. Many people don't even consider this cryptocurrency to be a cryptocurrency. It saw huge growth in 2017, much bigger than BTC itself, and was one of the fastest growing cryptocurrencies of 2017. There are 35 billion coins on the market. However, there are as many as 100 billion of them—most of them (up to 62%) are owned by the private company that founded the cryptocurrency.