For the convenient study of vast science Ayurveda, is divided into eight branches, which are together called as Ashtang Ayurveda.
The eight branches are:
  
1. Kayachikitsa-Medicine,
2. Bala chikitsa- Pediatrics, 
3. Graha chikitsa- Bhut Vidya 
4. Urdhvanga chikitsa-Treatment of eyes, ears, nose, throat and head,
5. Shalya chikitsa -Surgery, 
6. Damstra chikitsa-Toxicology or agad tantra,
7. Jara chikitsa-Rasayana, 
8. Vrishya chikitsa (vajikarana)- Virilification.
 
In Kayachikitsa that is medicinal branch includes all the diseases situated in the body like fever, etc
Actually Kaya means body and also digestive fire and chikitsa is (treatment) so it is 
Kayachikitsa.
Bala-chikitsa is that branch that includes matter related to children.
The diseases suffered by children and the treatment given for curing is Bala-chikitsa.
Graha chikitsa bhut vidya is that branch or subdivision of Ayurveda and mainly deals with the management of psychic disorders of human beings produced as a result of invasion by some evil spirits.
Urdhvanga means the organs situated above the neck and chikitsa-treatment of eyes, ears, nose, throat and head is Urdhvanga chikitsa or shalakya
Shalya chikitsa  it is the branch of Ancient Indian surgery that describes in detail about the pre-operative procedures, general procedures, post-operative procedures, marma's (vital points) and also about anesthesia. The description of the types of bandages, shastra (sharp instruments), yantras (blunt instruments), and sutures (stitches) has been described in this surgery 
Damstra chikitsa toxicology or agad tantra is the branch including the science of poisons
Jara chikitsa rasayana or the rejuvenating therapy is the therapy which, promotes and preserves health and longevity in the healthy person, and to cure diseases in the sick.
Vrishya chikitsa(vajikarana) virilification is that branch which includes drugs that are mainly used for improving fertility. They serve as good aphrodisiacs and induce an immediate sense of pleasurable excitement, along with increased fertile seminal secretions even in an ageing person. These drugs also increase the strength and stamina of the person. All this is included in Vrishya chikitsa