made from a nylon mesh material formed into a cap that is then hand-ventilated by knotting single strands of hair into the tiny openings of the cap, giving the hair a more natural and authentic continuity than typical extensions. It has few variations including straight, wavy and curly. Furthermore, the extension units can be woven in or attached to a person's hairline with special adhesives. To ensure a proper fit, head measurements are taken into account with this type of weave. A lace frontal is best placed by a professional since more advanced weaving and hair extensions are used. This method is commonly used because it makes it possible to have access to a certain part of the scalp. Tracking involves the braiding of a person's natural hair. This is one of the most commonly used methods as it is quite fast and lasts considerably longer than other techniques. However, it does not allow for regular hair maintenance. In order to prevent the hair from being bumpy or uneven, the hair is sewn horizontally or vertically across the head from one side to the other starting from the bottom. The braided hair is then sewn down and the hair weft extensions are sewn onto the braids. A weave can consist of a few tracks, or the whole head can be braided for a full head weave. With a full head weave, the braids are sewn down or covered with a net. Extensions are then sewn to the braids. The number of tracks used depends on the desired look. Types of hair The most popular and commonly available form of hair is known as premium hair. It is sold in most beauty supply stores or online. The roots and tips of hairs are interwoven in premium hair which causes tangling. This is due to the opposing cuticle layers catching onto one another. However, as it is the most inexpensive type of hair, it is a best seller. Premium hair comes in two types: Regular premium hair: generally the least expensive type of hair. The cuticles are present in different directions and the hair is prone to tangling. "Tangle-free" premium hair: this is obtained by chemically removing the cuticles using an acid bath. This process reduces the friction among hairs, leaving the remaining hair tangle-free. In order to give the appearance of natural healthy hair, a laminate is applied to the hair