In general, oils are any slippery or viscous, non-water-soluble substance derived from animals, minerals, vegetables or synthetic sources. Most oils are liquids at room temperature and their viscosity makes them excellent for lubrication. In Ayurveda, oils are used both externally and internally to help tissues like blood and lymph flow effortlessly through the body. Most Ayurvedic oils are plant or mineral based because Ayurveda generally does not permit any sentient being, including animals, to be harmed. Whether plant, mineral, or animal-based, Ayurvedic oils are used to treat any ailment caused by an imbalance in doshas, or, internal tissues/ humors. Oil therapies are most helpful in treating a variety of ailments, especially diseases of the nervous system, bones, and deeper tissues.