Why do you use soap to wash your hands?

When you have your hands covered with water, THAT'S the time where you have to use soap, the soap can ONLY clean your hands when you're hands have water if you only use water to wash your hands then your hands will still be dirty. When you use make sure you use only 1 pump cause if you use more than 1 pump then that won't be good for your hands cause soap has chemicals.