Smell is the most sophisticated dog senses. Dogs are more familiar with things by smell than humans perceive them. Dogs can recognize some of the most vulnerable smells of millions of times that humans recognize, and a dog can smell a bunch of things by extracting those touched by a particular person. The tip of the dog's nose preserves moisture by means of a fluid excreted from the gland inside the nose, which helps the dog's moisture to distinguish odors. The dog also sniffs its nose to keep it moist, and the dog's mustache can determine the direction of the wind and helps the dog determine where the odor came from.