Dog communication is the transfer of information between dogs, as well as between dogs and humans. Behaviors associated with dog communication are categorized into visual and vocal. Visual communication includes mouth shape and head position, licking and sniffing, ear and tail positioning, eye gaze, facial expression, and body posture. Dog vocalizations, or auditory communication, can include barks, growls, howls, whines and whimpers, screams, pants and sighs. Dogs also communicate via gustatory communication, utilizing scent and pheromones.'Small dog watching a cat on a table''Dog approaching another dog with hostile intentions''Dog in a humble and affectionate frame of mind''Dog caressing his master''Half-bred shepherd dog''Head of snarling dog' Dog communication is the transfer of information between dogs, as well as between dogs and humans. Behaviors associated with dog communication are categorized into visual and vocal. Visual communication includes mouth shape and head position, licking and sniffing, ear and tail positioning, eye gaze, facial expression, and body posture. Dog vocalizations, or auditory communication, can include barks, growls, howls, whines and whimpers, screams, pants and sighs. Dogs also communicate via gustatory communication, utilizing scent and pheromones. Humans can communicate with dogs through a wide variety of methods. Broadly, this includes vocalization, hand signals, body posture and touch. The two species also communicate visually: through domestication, dogs have become particularly adept at 'reading' human facial expressions, and they are able to determine human emotional status. When communicating with a human their level of comprehension is generally comparable to a toddler. Humans can artificially alter how dogs communicate with other dogs and with humans by surgically cropping their ears and docking their tails. These procedures can have a strong impact on how dogs communicate and interact for the rest of their lives