You can simply check coinmarketcap if the Coin/Token/Crypto exists. Soon, as you progress more in engaging to crypto community, you'll learn what's a real crypto and what's not. Crypto exchangers that supports coins/token exchange are mostly shits and were only promoted by those scammers. There are numerous events back then that exchangers supported token and their token address to be exchanged on real crypto yet it wouldn't work unless there would be some buy order on the market. Also, if your really wanted to know more about such topic, better try browsing on trading discussion, as you've seemed to be interested in how trading works.
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