Hair extensions, or weaves, are made out of either synthetic or natural human hair and come in a variety of different attachment methods. The extension fibers are attached to either clips, glue, micro rings, or netting so that they can be integrated into a person's natural hair.
When hair extensions are made out of human hair, it is very important that the roots of the individual hairs are all aligned, or else the cuticles will be running in different directions. Poor root alignment can cause the hairs to snag and tangle, and so hairs must be hand sorted. This process is very expensive, however, and so cheaper extensions made of actual human hair have often had the cuticle stripped to prevent tangles. Cuticle stripping decreases the quality of the hair, making it more brittle and susceptible to damage. Remi hair is hair that has been sorted so that the cuticles are aligned and do not need to be stripped.
Because human hair is better than synthetic hair for weaves, there is a market for people (mostly young women) to sell their hair. "Virgin," or hair that has never been dyed, is preferred for the making of hair extensions and wigs. Hair must be in good condition without split ends and of a certain length so that it can be knotted onto the netting and still have good length. According to Business-standard.com, India is one of the world's leading sources for human hair.
Hair extensions are often referred to as "weaves" because of the popular method in which they are sewn, or woven, into the wearer's natural hair through a method called tracking. Tracking involves braiding the native hair into cornrows, and then sewing the extension onto the braids.