Siddha Yoga and Related Resources:
Siddha means the perfect one, the self-realized one, an adept, the pure one, a yogi who has overcome all the impurities of the mind and body and achieve self-absorption, a great devotee of Shiva, etc. The word is used in Indian religious and cultural expressions as a reference to a spiritually accomplished master or the state of liberation or enlightenment.
Siddha may also refer to yogis who have has attained siddhis or paranormal capabilities. Broadly speaking, siddhars, naths, ascetics, sadhus, yogis, tantriks, gurus, who practice sadhana may be considered Siddhas especially if they have advanced on the path and awakened to the highest reality.
In Jainism, it is used to refer the liberated souls who have destroyed all karmas and have obtained moksha. They are free from the trans migratory cycle of birth and death (samsara) and are above Arihantas , the omniscient beings. Since they are souls in the purest form, they do not possess corporeal bodies. They are formless, free from passions and temptations and reside in the Siddhashila at the top of the Universe. According to the Jain texts, they also possess eight distinct qualities such as infinite power, infinite bliss, infinite knowledge, changeless and so on.
In Tamil Nadu, South India, a siddha (see Siddhar) refers to a being who has achieved a high degree of physical as well as spiritual perfection or enlightenment. The ultimate proof of it is that they achieve physical immortality. It is said that they use various techniques include the use of certain chemicals to purify and perfect their minds and bodies and engage in prolonged, undisturbed meditation. For more information on Siddhas, please check the following links.