Your back consists of three main muscles, latissimus dorsi (middle back ), rhomboids and erector spinae (lower back). These muscles with other smaller supporting back muscles are a key figure when you are moving your body around. So It is a good idea to keep your back muscles in good shape. Lower back or Erector Spinae is located along the lower part of your spine. Lower back supports the upper body and it used to extend and flex your spine, from this you can imagine that there aren't many tasks you can do without activating your lower back muscles.
When exercising your back in general, you have to be really careful and never let your back to arc! Always do the exercises with straight back, when you are lifting anything. Never use too big weights as this will increase the chances of a back injury, always use weights which with you can execute the exercises in a controlled manner.