Exchange test environments and demo modes
Some exchanges run a separate test environment, often called a testnet, or a demo mode inside the main app. Their big strength is the interface. You learn the exact buttons and order forms of that one exchange.
As of this writing, many of these run on their own order books with test funds, so prices and depth can drift away from the main market. Some are aimed at developers testing code more than at people learning to trade. Check the exchange's own docs for how its version works today.