A playing card refers to a special card used in playing card games and gambling.

The most common type of playing card and the most likely to be encountered on e621 is the international (French) 52-card deck or one of its variants (which are often only distinguishable by the number of cards used in the deck; an example is the pinochle deck which uses two copies each of 24 cards to make a total of 48 cards).

post #4291103

Other varieties include various non-fortune telling variants of tarot cards, Spanish/Italian-suited decks, German-suited decks, Swiss-suited decks and so on.
post #4792907 – Tarot Nouveau

post #5277632 – German suits

post #5274841 – Spanish suits

International (French) Cards

• 2-10, Jack, Queen, King, Ace in the following four suits:
• ♣ – clubs_(suit)
• ♦ – diamonds_(suit)
• ♥ – hearts_(suit)
• ♠ – spades_(suit)
• 0, 1, 2 or more jokers, usually distinguishable by color
• A tarot deck adds the knight rank between jack and queen, 21 permanent trumps and one Fool, but may remove other ranks
• Traditionally, clubs and spades are colored black while diamonds and hearts are colored red, but other combinations are possible, such as green clubs and blue diamonds or green spades and yellow diamonds.

German Cards

• 6 (or more often 7)-10, Unter, Ober, King, Ace in the following four suits:
• ♦ – bells_(suit)
• ♥ – hearts_(suit) (shields_(suit) in Switzerland)
• ♠ – leaves_(suit) (roses_(suit) in Switzerland)
• ♣ – acorns_(suit)
• In most games the 10 is elevated to be between the ace and king in trick-taking power.

For more information:

• Playing Card (Wikipedia)
• Tarot, Tarock, and Tarocchi Games (Wikipedia)