The word Siddha has its origin in the Tamil word “Siddhi” which means "an object to be attained" or "perfection" or "heavenly bliss". India being the birth place of many traditional philosophies also gave birth to Siddha.

The system of medicine is believed to have been preached by Lord Shiva to his consort Paarvathi, then by Her to Nanthithevar (the holy bull mount of Lord Shiva) who passed on the knowledge of Siddha to Siddhars for the benefit of humanity. Siddhars are people who have attained heavenly bliss (Siddhi). They developed and practised the eight levels of Yogam to attain eternal bliss, viz., Attaanga Yogam.

These eight levels are:

Iyamam	Good thoughts
Niyamam	Good deeds
Aasanam	Posture of the body
Praanaayaamam	Control of breath
Prathiyaakaaram	Restraint of senses from their objects of enjoyment
Thaaranai	Focusing of mind
Thyaanam	Profound meditation
Samaadhi	Super consciousness

Siddhars were also said to possess eight remarkable powers called Attamaasiddhigal which are Animaa, Magimaa, Lagimaa, Karimaa, Praapthi, Prakaamiyam, Vasithuvam and Eesathuvam. Many Siddhars are considered to have contributed to the Siddha system of medicine and among them, Agathiyar is considered to be the foremost Siddhar. Their contributions were mainly classified into the following four categories:

                      i.     Gnanam             Spiritual knowledge

                     ii.     Yogam               Yogic Principles, meditation techniques

                    iii.     Vaatham            Alchemy and the like practices

                   iv.     Vaithiyam           Medical practices

Each of these practices is aimed towards maintenance of a healthy body and healthy mind which forms the basis to attain eternal bliss. The Siddha system in its unique approach stresses upon several routine and seasonal regimen as preventive measures against illness of body and mind. This system lays significant emphasis on diet as it plays a very important role in the maintenance of a healthy body - the ground which nurtures a healthy mind.

The basis of the Siddha system is the physiological doctrine of three humors viz., Vali, Azhal and Aiyam collectively known as Uyir Thaathukkal. Accordingly, each individual is considered to have a unique body composition and this system of medicine has an individualistic approach in the preservation of health.