Types of cards:
- mature: A mature card is one that has an interval of 21 days or greater.
- young: A young card is one that has an interval of less than 21 days, but is not in learning.
- relearn: A relearning card is a card that you have failed in review mode, thus returning it to learning mode to be relearned.
- unseen: An unseen card is one that has been added to your collection but has not yet entered learning mode. Unseen cards are sometimes referred to as “new” cards, especially when they are in the “new” queue to be shown for the first time.