Playing cards have been around since at least the 14th Century, although the deck of 52 that is most commonly used today is quite different from decks of cards invented by Asian peoples. When individuals play solitaire today, whether digitally or with paper cards, they’re accustomed to the deck with four suits and its royalty, also known as the court. Some potential reasons for the numbers and images are straightforward, but others are mysterious.

For instance, the 52 cards are likely to represent the 52 weeks of the year. It’s not certain, but the four suits could represent four seasons. When people play solitaire, they know there are 13 cards for each suit. The reason for this is unclear, but it might relate to moon cycles. Even though there are 12 months, the moon actually goes through its phases 13 times annually, with 28 days per cycle.

The images on the cards do not have to always be the same, but manufacturers of paper cards make them relatively standard. The queens hold flowers, for example. That’s not always the case in free online solitaire games. Some digital cards may only have the faces of the kings, queens and jacks, which also are known as knights or knaves. Game designers know that digital players often don’t care much about the artistry of the cards; they just want to pass the time and have a bit of fun. They easily recognize the royalty by the J, Q or K in the corners. The faces on the cards immediately alert them that those are not any of the numbered pieces.

Early decks had a variety of colors, but eventually the cards came to have the standard colors of red and black. The red suits are the hearts and diamonds, whereas the black suits are the spades and clubs. Games of classic online solitaire don’t have the one extra card that is often added to the deck of 52. That odd card is, of course, the joker; some decks even have two of them. Yet the joker isn’t needed for playing solitaire or for most card games.