Fat, also lipid, is a general term for a variety of substances which generally are triesters of glycerol and fatty acids. Fats are generally not soluble in water but are soluble in organic solvents. Various fats may be solid or liquid at normal room temperature. The term "oil" is often used to refer to fats that are liquid at normal room temperature, while "fats" is usually used to refer to those which are solid.
Edible fats, including animal fats and vegetable fats (vegetable oils), are an important component of the human diet. Fats are the carriers of several important vitamins, and are also an important source of food energy (calorie).
Lack of adequate food energy is a continuing problem in many areas of the developing world and in famines, resulting in malnutrition, disease, and deaths; while in the developed countries over-consumption of fats leads to obesity and serious health problems.