Hello, crypto-exchanges are places, rather, not of exchanging cryptocurrencies, but of speculative earnings on courses. There are quite a few of them: Binance, Kraken, Huobi and many others. On the exchanges, as a rule, there are quite large turnovers, that is, there are a lot of transactions, so the commissions here are lower than in exchangers. At the same time, the percentages for the cryptocurrency exchange that they charge will differ from one trading platform to another.