The contributors of Siddha system, the Siddhars, of Tamil land, were mystics, yogis, poets, devotees, seers and medical men of various combinations and various statures. They were super human beings who possessed supernatural powers (like Eight types of Siddhis). They were the greatest scientists of ancient times and were the guardians of the world and they existed, and still exist, for the benefit of the public at large. They were men of great practical knowledge and wisdom. They had full awareness of the nature and activities of all the objects in this planet and of all times-past, present and future. They were mainly responsible for the growth and development not only of Tamil medicine that includes alchemy, medicine, yoga, kayakalpa (rejuvenation therapy), philosophy, astronomy, astrology, varma, muppu, thokkanam etc., but also for many other sciences of public utility.
The therapeutic treatment in Siddha could be further categorized into Purgative therapy, Emetic therapy, Fasting therapy, Steam therapy, Oleation therapy, Physical therapy, Solar therapy, Blood letting therapy and Yoga therapy. These are prevention or treatment of diseases, and postponement of death (to any desired length of time).