Dogs have an incredibly powerful sense of smell, estimated to be “anywhere from 10,000 to 100,000 times more powerful than that of humans.” Because of this, behaviors that seem awkward to people are completely normal for dogs and part of how they understand the world.

While sniffing can be “often amusing or embarrassing,” it is not rude or inappropriate in a dog’s mind. Smelling is how dogs gather detailed information when they meet someone new or notice a change in a familiar person.

Dogs “rely on their noses to gather information about their surroundings and the people they encounter.” Unlike humans, they don’t depend mainly on sight or sound, but on scent to form first impressions and recognize individuals.

They also have “a special organ called the Jacobson’s organ (vomeronasal organ),” which plays a key role in detecting scents that humans cannot perceive. This organ allows dogs to process much more complex chemical information.

Through this system, dogs can detect “chemical signals known as pheromones.” These signals can reveal “a person’s hormonal changes, emotional state, and even health conditions,” which explains why certain areas of the body attract more attention from a dog’s nose.