Threading is an ancient Middle Eastern hair removal technique. In this technique root takes longer to grow back because it removes hair by the follicle and a new root must grow before the hair can re-emerge. 

Advantages cited for eyebrow threading, as opposed to eyebrow waxing, are that it provides more precise control in shaping eyebrows and is gentle on the skin. 

There are a few different techniques for threading, These include the hand method and mouth method. With the thread wound between the fingers and then pressed against the base of the hair and pulled from the roots. There are no chemicals or waxes involved in this method. Each technique has advantages and disadvantages; however, the mouth holding method is the fastest and most precise.