A deck of Uno consists of 108 cards. The deck includes cards in four different colors: red, blue, green, and yellow. There are 25 of each color (0-9), and each color also includes two draw two cards, two skip cards, and two reverse cards. In addition, there are four wild cards and four wild draw four cards. The wild cards and draw four cards can be played at any time, while the other cards must match either the color or the number of the previously played card.