In its most common form, American cheese is a blend of milk fats and solids, whey protein, other fats etc. It is not usually considered "cheese" nowadays but there was a time when American cheese was made with a blend of cheeses like cheddar, Colby etc. Since these blends originated in America, the cheeses got the name American cheese. They were earlier sold in blocks but with change in time they are now commonly available in slices, cubes etc also. Over the recent years, American cheese is available in yellow, white and pale orange colour. "Annato" is added as common colouring agent in these cheeses.