Throughout the world, there are approximately 3,000 essential oils, most of which are used only in the local regions in which they are found. About 30o are in more general use, and are traded worldwide. It is help¬ful to know where a particular oil comes from because, for example, geranium oils grown in Egypt, China, or Madagascar each have their unique characteristics. Also, the same species of plant will produce an oil with different properties depending on whether it was grown in dry or damp earth, for example, or at high or low altitude, or in a hot or cold climate.