Every time you rate a card, we schedule when you should see it again. Cards you find easy come back less often, while ones you mark again or hard return sooner, so you spend your time on what you don't know yet. A card is never added to your due queue until you've seen and rated it at least once. And once you've rated a card easy ten times, it's considered mastered and drops off the due schedule entirely. Use Review Due Cards to study just the cards that are scheduled for today, or pick decks below to study whatever you like.