Many people start their dreads by separating hair with rubber bands. This is a great way to start dreadlocks. After a week or so however, rubber bands will start slipping down the dreadlock. After a month or too these rubber bands will start to break off/break apart. This is when the thread comes in.
I have not found too much online about using thread in replace of bands. I decided to try it myself. I have had the thread in for just about over a month now. I find that they don't slip as much as rubber bands, and (unless its not wrapped enough) tends to stay on longer than rubber bands.
I will be posting some videos later about hot to thread roots.