more definition, less sensitivity
Threading is an ancient method of hair removal originating in India.
A thin (cotton or polyester) thread is doubled, then twisted. It is then rolled over areas of unwanted hair, plucking the hair at follicle level. Unlike tweezing, where single hairs are pulled out one at a time, threading can remove short lines of hair.
Advantages cited for eyebrow threading, as opposed to eyebrow waxing, are that it provides more precise control and defined shape for eyebrows and is gentler on the skin.
It can be painful as several hairs are removed at once: however done professionally, this can is minimised.