At present, we can only trade on the exchange. The so-called currency circle exchange is actually equivalent to a centralized trading platform. We all put our own coins on it for trading, and the platform provides us with technology, security, transactions, etc.  And so on, they charge a little transaction fee.
 If we want to use trading platform services, we must completely trust them. Putting coins on this platform is equivalent to putting my own money in other people's pockets.
 Others can actually dispose of our assets at will.
 So be sure to find a large platform with high reputation and reliability.