5-alpha reductase: An enzyme which converts testosterone to dehydrotestosterone. This is the hormone which causes androgenic alopecia in the individuals who are genetically susceptible.

Acne: Acne is an inflammatory disease of the pilosebaceous unit.

Alopecia Areata: A patchy baldness usually of temporary nature. Cause unknown but anxiety and stress are common precipitating factors.

Alopecia Totalis: Total loss of hair of the scalp either within a very short period of time or from progression of localized alopecia.

Alopecia Universalis: Total loss of hair from all part of the body.

Anagen: Growth phase of the hair cycle, lasting about 3-6 years in human scalp hair

Androgenetic Alopecia: This is the term for male or female pattern baldness which depends on the genetic predisposition of the hair follicles and the levels of DHT in the body.

Androgens: A class of sex hormones associated with the development and maintenance of the secondary male sex characteristics, sperm induction, and sexual differentiation.

Antiandrogen: A substance which interferes with the function of an androgen, or male sex hormone, by taking over the androgen's receptors.

Catagen: The catagen phase is the resting phase of the hair cycle.

Cortex: The cortex is the main structure of the hair shaft. The cortex determines the color and texture of the hair.

Cyproterone Acetate: This drug is normally used to reduce sex drive in men who have an excessive sex drive. It is also prescribed to treat hirsutism and androgenetic alopecia in women.

Dermal papilla: The dermal papilla is situated at the base of the hair follicle. The dermal papilla contains nerves and blood vessels which supply glucose for energy and amino acids to make keratin.

DHT (Dihydrotestosterone): DHT is a male hormone that is suggested to be the main cause for the miniaturisation of the hair follicle and for hair loss. DHT is formed when the male hormone testosterone interacts with the enzyme 5-alpha reductase.

Eumelanin: Eumelanin, a kind of melanin that dyes hair black to brown.

Finasteride: Finasteride is the generic name of the brand name drug Proscar. Proscar is manufactured by Merck and is FDA approved for the treatment of benign prostate enlargement. More recently, 1mg tablets of finasteride have been marketed under the brand name Propecia as a treatment for hair loss.

Follicle: The hair follicle houses the root of the hair.

Gene Therapy: Gene therapy is a treatment method which involves the manipulation of individuals genetic makeup.

Hair Cloning: A technique under development which could make an unlimited crop of donor hair available for transplanting.

Hair Weaving: A process by which hairpiece is attached to existing hair on the head through braiding or weaving process.

Keratin: A kind of protein that is present in hair and nail.

Minoxidil: Minoxidil is the generic name of the brand name drug Rogaine. Rogaine is manufactured by Pharmacia & Upjohn and is FDA approved for the treatment hair loss. Minoxidil is available in the form of a topical lotion with varying strength from 2% to 5%. Minoxidil was the first drug to be approved by the FDA for the treatment of androgenetic alopecia.

Medulla: The medulla is a central zone of cells present only in large thick hairs.

Melanin: Melanin from pigment cell is responsible for the coloration of hair.

Pheomelanin: Pheomelanin, an iron rich pigment, dyes hair yellow-blond to black.

Punch Graft: The old-fashioned way of removing grafts for hair transplants usually carried out with an instrument called a trephine.

Retin-A or Tretinoin: Retin-A is a brand name for a topical gel or cream normally used in the treatment if acne.

Saw Palmetto: Saw Palmetto is a Natural Herb That has been shown to be an effective antiandrogen.

Scleroderma: A disease of the skin and connective tissue that can cause hair loss over the affected areas.

Sprionolactone: This is a drug normally used to treat high blood pressure; however, it also acts as an antiandrogen and is used in the treatment of androgen related disorders such as female pattern baldness and hirsutism.

Telogen: It is the last or the resting phase of the hair growth cycle.

Terminal hair: Large, heavy pigmented hairs with a central medulla.

Testosterone: A predominantly male hormone which promotes the development of male characteristics.

Traction Alopecia: Traction Alopecia is the condition of hair loss due to the traction place on hair. It is mainly seen with braid or different hairstyles that create traction on the scalp.

Trichotillomania: Trichotillomania is an Impulse-control disorder defined as recurrent pulling of one's own hair that results in considerable hair loss.

Vellous hair: Vellous hair is very short, fine light colored hairs