Nowadays, there are an absolutely insane number of cryptocurrencies and tokens out there wandering around the internet. Each with their own independent ecosystems and each with their own specific use case. When you find yourself in need (or want) of one of these tokens you'll quickly find that discovering how to acquire it can be a massive battle all its own. Usually, you must go to a centralized exchange, buy a base asset to the ecosystem your token resides in then send your asset to a decentralized exchange where you can swap the base asset for the token you want, then you will be free to move that token to a wallet where it will be useful.