Hair Growth Cycles
Hair is genetically designed to follow its own natural growth cycle, which consists of three repeating phases: anagen (hair growth), catagen (follicle transformation), and telogen (the resting/shedding period). During anagen, the hair follicle begins to emerge from its pore while oil is produced by sebaceous glands to protect and condition hair. Throughout catagen, the hair follicle shrinks because a part of it is destroyed and the dermal papilla breaks away to rest and rejuvenate. This phase can last anywhere from two to three weeks. During telogen, the hair remains in the follicle for about three months and is gradually shed during exogen.
The anagen cycle is the ideal phase for hair removal because the hair is actively growing from the bulb and is rooted deep in the follicle. In this stage, certain hair removal techniqes may even be able to remove the bulb as well. Hairs that emerge a few days after hair removal are in the anagen stage and either had not reached the surface of the skin at the time of the treatment or were not long enough to be removed.

Hair Types
There are three different hairs types that can be found on the human body: lanugo, vellus, and terminal. Lanugo is a downy, unpigmented hair found on fetuses and sometimes on malnourished children and adults. Typically, lanugo on newborns is shed within days or weeks and replaced with vellus hair. Vellus is short, fine, thin, light-colored, and barely noticeable. This type of hair is often seen around the lips, the back of the ears, some external genital areas, the navel, and scar tissue. Terminal hair develops out of vellus hair and is hair that develops during puberty in both boys and girls. Terminal hair becomes darker, coarser hair. The density of hair varies from person to person.

Hair-Removal Methods
Threading is an ancient Middle Eastern technique that is becoming common in the United States. This procedure is mainly used on the eyebrows, chin, and upper lip. The practitioner uses a doubled-up strand of cotton thread to twist around individual hairs and pull them out from the roots.
Sugaring is an ancient Persian technique that uses a sugar paste to remove unwanted hair. This paste only sticks to the hair and is applied at room temperature, eliminating the risk of burning the skin.
Waxing is semi-permanent and removes the hair from the root. In this method, wax is spread over the skin and removed against the direction of hair growth. When the wax is removed with a strip, it is often categorized as soft wax. When it is removed without a strip, it is referred to as hard wax.
Laser removes about 60 to 70 percent of unwanted hair. This treatment is not appropriate for everybody as it is only effective for those with light skin and dark, coarse hair. A narrow beam of concentrated light is focused on small sections of skin, destroying hair follicles and thereby preventing hair regrowth. This method requires multiple treatments with no guarantee that hair will not grow back.
Electrolysis is the only form of permanent hair removal that has been approved by the FDA. This treatment destroys the root of each hair with an electric current. It also has the benefit of working for all skin types. However, electrolysis can only remove one hair at a time, taking more sessions to complete the process.