Etymology
Ayurveda derives its name from the Sanskrit words "Ayu" (meaning Life Span) and "Ved" (meaning knowledge).

What is Ayurveda?
Ayurveda is an ancient Indian system of medicine that, the Hindus believe, is of divine origin. It treats by the law of contraries, which is also called Vipareetha Chikitsa. Dhanvantari is the God of Ayurveda. This system of medicine believes that the body is made up of the Panchamahabhutas (five elements) namely Prithvi (earth), Aap (water), Tej (divine fire), Vayu (air), and Akash (universal space) and basically consists of Sapta Dhatus (seven tissues) namely Rasa (life sap), Rakta (blood), Mansa (muscles), Med (fat), Asthi (bones), Majja (bone marrow), and Shukra (reproductory fluid); Malas (waste products) namely Purisa (faeces), Mutra (urine), and Sweda (sweat); and Doshas (humors) namely Vata (wind), Pitta (bile), and Kapha (phlegm). Ayurveda employs various herbs, elements, animal products, or combinations of these in the form of dravyas, tailas, churnas, etc.

Ashtanga Ayurveda
Ashtanga (eight-armed) Ayurveda comprises the following disciplines:
Kaya Chikitsa (Internal Medicine), Shalya Tantra (Surgery), Rasayana (Vitality and Longevity), Bhoota Vidya (Spiritual), Shalakya Tantra (Otorhinolaryngology [E.N.T.] and Ophthalmology), Vajikarana (Aphrodisiacs and care of the Generative organs), Agada Tantra (Toxicology), and Kaumara Bhritya Tantra (Pediatrics)

However, in the last five decades, additional disciplines have been added such as Ayurveda Siddhanta (Fundamental Principals of Ayurveda), Ayurveda Samhita, Rachna Sharira (Anatomy), Kriya Sharira (Physiology), Dravya Guna Vigyan (Materia Medica & Pharmacology), Ras Shastra, Bhaishajya Kalpana (Pharmaceuticals), Prasuti Tantra (Obstetrics & Gynaecology), Swasth-Vritla (Social & Preventive Medicine), Rog Nidan (Pathology), Mano-Roga (Psychiatry), and Panchkarma.

Modes of Ayurvedic treatment
    Rasayana therapy (Rejuvenative, remedial, and immunostimulatory medicines are administered)
    Shamana therapy (Attempts are made to correct or at least palliate the imbalanced doshas)
    Shodhana therapy (Panchakarma therapy is used to purify the system)
    Nidan Parivarjan (Avoidance of the triggering, aggravating, or maintaining causes is advised)
    Pathya Vyavastha (Advice regarding the patient's diet and regimen is given)
    Satvavajaya (Psychological counseling is done and mind control techniques are taught)

Panchakarma therapy
Panchakarma therapy, the most important part of Shodhana, is getting extremely popular in India as well as abroad. The main logic behind this therapy is to detoxify the system and increase the blood circulation to all the organs of the body. The increased tissue perfusion and cellular oxygenation facilitates repair and healing.

Panchkarma derives its name from the Sanskrit words "Panch" (meaning five) and "Karma" (meaning action). It basically involves five cleansing processes that purify the tissues and replenish the energy reserves of the body.

The three stages of Panchakarma therapy
Purva Karma (pre-treatment): It is the preparatory stage to enable easy expulsion of toxins from the system. Two processes are performed at this stage.
Snehana (Oleation of medicated oils is performed internally or externally)
Swedana (Fomentation in order to open up the channels of the body, the commonest ones being Nadi Swedana and Bashpa Swedana)
Pradhana Karma (main treatment): The five cathartic procedures are carried out at this stage.
    Vaman (Intentionally inducing vomiting)
     Virechan (Intentionally inducing purging)
     Niruha Basti (Enema using medicinal decoctions)
    Anuvasna Basti (Enema using medicinal oils) and
    Nasya (Instilling certain medicaments nasally)
Paschat Karma (post treatment): At this stage, advice and prescriptions regarding Anna (diet), Vihara (regimen), and Aushadha (medications) are given.

The Ayurvedic Controversy
The Dietary Supplement Health and Education Act in the US regulates Ayurvedic and other herbal medicines, which are classified as dietary supplements. Certain Ayurvedic products were found to contain lead, mercury, and arsenic in higher than permissible quantities. Fear of the toxic effects of these medicines lead to their ban in many countries all over the world. The Ayurvedic physicians, however, have stood up in defense and claim that Ayurvedic drugs that are prepared from substances that are dangerous in their crude form are treated by a detoxifying process known as a ‘samskara.’ A popular example given is that of the Aconite root, a toxic and very poisonous substance in crude form, 2.6 mg of which proves to be the fatal dose for laboratory mice. When processed by a samskara in which the root is boiled twice in cow’s urine and twice in cow’s milk, the root is rendered totally harmless to such an extent that administering this treated root in even eight times the amount of the fatal dose of crude aconite shows no toxic effects in laboratory mice. A lot of research is yet going on to prove this point. However, many Indian manufacturers have started altering the composition of their products as per the rules and regulations of the western world.