Fat is one of the three main macronutrients: fat, carbohydrate, and protein. Fats, also known as triglycerides, are esters of three fatty acid chains and the alcohol glycerol.The terms "oil", "fat", and "lipid" are often confused. "Oil" normally refers to a fat with short or unsaturated fatty acid chains that is liquid at room temperature, while "fat" may specifically refer to fats that are solids at room temperature. "Lipid" is the general term, as a lipid is not necessarily a triglyceride.