If you are new to the cryptocurrency market, it is best to start with digital asset pairs that include fiat currency. These are known as crypto-fiat pairs, not least because traders will be trading fiat currency against the digital token's currency.
Traders must trade ADA/USD if they want to speculate on the exchange rate between Cardano and the US dollar.
If the price of ADA/USD is $1.08, the trader must inform their chosen broker whether they believe the pair will rise or fall.
The vast majority of trader-selected crypto-to-fiat transfers will always include the US dollar. This is because, like when trading precious metals or oil, the US dollar is the reference currency in the cryptocurrency market.