How does your body know how to grow hair back when it is cut?

Like eybrow hair for instance....it grows to a certain point and then stops..but if you cut it somehow ur body know that u cut it and it grows back?!? dont get it! explain to me pleaseHow does your body know how to grow hair back when it is cut?
Your body is always making your hair grow... When your hair is long it's harder to tell that your hair is growing, but when it's cut shorter then it's easier to tell that it's growing compared to the longer hair... But your eyebrows, for instance, they stop growing at a certain length and eventually fall out and grow back again.... And for the hair on your head... it's always growing, but when the ends are cut they are made healthier and they continue to grow faster than the hair that has split-ends would... That's why people get the idea that ';if you continue to cut your hair it'll grow longer';How does your body know how to grow hair back when it is cut?
welll ur hair never realy stops growin like ur hair it doesnt stop growing but when u cut it its still gonna grow your body doenst really know its just that it never really stops growin
its got smart technology