There are 26 red cards in the standard 52 card deck. The red cards are the diamond and heart suits, and the black cards are the club and spade suits.
Playing cards were invented in China as early as the 9th century and appeared in Europe as early as the 14th century. The four common suits are the spade, diamond, heart and club. These suits originated in France, with the club representing an acorn and the spade representing a leaf. It has been theorized that the standard 52-card deck correlates to the natural world, with the four suits relating to the four seasons.