Traction alopecia is caused by the constant tugging and pulling of hair caused by very tight: Braids/extensions, cornrows, twists, weaves, pulled back styles, pony tails etc. Although these hairstyles can be low maintenance, the frequency with which they are done and the degrees of tightness applied to the hair will determine what extent of hair loss will be experienced over time. You can also experience traction alopecia by tying head scarves tightly around hair line especially when going to sleep. Any material that will create friction and cause the hair to hold on to it will cause some level of hair loss.
Here is an analogy to help you fully understand why constantly yanking out strands of hair by the roots is bad for you, Most of us women tweeze our eyebrows right? If we tweeze them enough times, the areas from which we continuously pull out hair stop growing hair. The hair starts coming in thin and as we continue tweezing and pulling it out by the root, it stops coming in. This same response will be experienced if your hair strands are held too tight repeatedly such that they get plucked out. This type of hair loss is mainly experienced around the temples or more generally around the hairline. Over time, growth of hair in these areas can be slowed down. In serious cases, the hair roots are permanently damaged and the hair stops growing altogether.