Vegetable fats and oils are substances derived from plants that are composed of triglycerides. Nominally, oils are liquid at room temperature, and fats are solid; a dense brittle fat is called a wax. Although many different parts of plants may yield oil, in actual commercial practice oil is extracted primarily from the seeds of oilseed plants.
The temperature-based distinction between oils and fats is imprecise, since definitions of room temperature vary, and typically any one substance has a melting range instead of a single melting point.
Triglyceride vegetable fats and oils include not only edible, but also inedible vegetable fats and oils such as processed linseed oil, tung oil, and castor oil, used in lubricants, paints, cosmetics, pharmaceuticals, and other industrial purposes. Although thought of as esters of glycerin and a varying blend of fatty acids, in fact these oils contain free fatty acids and diglycerides as well.
