Red is the color of blood, rubies and strawberries. It is the color of the wavelength of light from approximately 620–740 nm on the electromagnetic spectrum. Next to orange at the end of the visible spectrum, red is commonly associated with danger, sacrifice, passion, fire, beauty, blood, anger, Christmas, socialism, communism, and in China and many other cultures, with happiness.
Red, black and white were the first colors used by artists in the Upper Paleolithic age, probably because natural pigments such as red ochre and iron oxide were readily available where early people lived. Madder, a plant whose root could be made into a red dye, grew widely in Europe, Africa and Asia. The cave of Altamira in Spain has a painting of a bison colored with red ochre that dates to between 15,000 and 16,500 BC. Red was also the first color, after black and white, to have its own name.