Why is the hair in your face called the bangs?

Bangs are the style name in the US. In the UK they are called fringes. Wikipedia extrapolates that they are named after the style of bobbing horse's tails straight across called "bang tailed". An interesting note is that the style has been around as a fashion cut since the seventh century. See the link for Ziryab, the noted fashionista and celebrated style guru of the Islamic world.