This video does not belong to me but was taken off YouTube.
Not only does skipping work your legs it works your whole body out. Your arms have to turn the rope and that roiling action increases the strength of the muscles in your forearms. It is also a good cardio work out as it gets the heart pumping, therefore your lungs will also be working hard to increase the oxygen intake. Doing 100 skips everyday does aid in increasing your strength, flexibility and fitness.