The broadest classification of life splits all organisms into three groups called domains. The three domains of life are bacteria, archaea and eukaryota.

Like carbohydrates, fats provide energy to the body. The difference is energy from fats tends to be longer burning as opposed to the quick fuel provided by carbohydrates. Fats come in three types, saturated (meats, shellfish, eggs, milk), monounsaturated (olives, almonds, avocados), and polyunsaturated (vegetable oils). Saturated fats can raise LDL ("bad") cholesterol while unsaturated fats can decrease it.

The liver produces bile which emulsifies (separates) fat.

A substance undergoes a phase transition when it moves from one state of matter to another, for example, when water freezes or boils.

An element in a solid state has atoms or molecules that are constricted and do not move freely. Solids maintain a constant volume and shape and exist at a lower temperature than liquids or gases.