The dog is a person best friend, but it also has its particular attitude, its privacy and moreover it needs specific restrictions. Showing teeth, growling and biting are the manifestations of the many emotive states of the dog, which you should identify as soon as possible to bring it to normal. It often is a transitory phase, but you should not underestimate it.
The reasons why a dog bite
Dogs are very different from people and have a very restricted range of manifestations when they have to express discomfort or a problem. Biting is often an instinctive reaction to something they find intolerable in that moment, like when we invade their space or when we touch their things and they do not want to share them with us, or simply for fear.
What t dog if the dog bites you
Definitely you have to avoid those situations when the dog bites, at least if you cannot find a reason to work on. At first you can try some homemade reductional exercises, but in order to obtain concrete results the best is to trust some canine educator, moreover if the dog is adult and we have adopted it recently. Only a specialist can tell us if these behaviors are just a phase or a dangerous attitude.
What to do if we have kids at home and the dog bites
Usually children are members of the family with whom the dog feels a special bond of protection, but it is not always like that. With their voices, their continuous invasions and their bursts of affection they can make the dog feel uncomfortable. Obviously, we are talking about children up to 3-4 years of age, less likely to understand some warnings from the dog. Not every breed or dogs are good for kids, actually some widely loved breeds have a fierce character, less likely to get along with humans: it is better to approach them gradually, because even the most meek dog may be a little jealous sometime.