The basic reason for having a laptop backpack is to help you carry you laptop around while leaving your hands free. The second reason is protection. Protection against scratches, protection against damage if you accidentally drop it etc… Quite a big part of the protection, depending where you live and where you take your laptop of course, is protection against water. Water and computers and other electronics in general don’t go well together. You could say they are worst enemies. This is where a waterproof laptop backpack comes in.