Yellow and red combine to make orange. Orange is a secondary color while yellow and red are primary colors. All colors can be made from a combination of the three primary colors: yellow, red and blue.
There are many different shades of orange, and the exact shade produced depends on the ratio of yellow to red. Other colors may be mixed in as well to lighten or darken the shade. Orange can also be mixed with the primary colors to produce tertiary colors yellow orange and red orange. On the color wheel, the color directly opposite orange and, therefore, considered its complementary color, is blue.