As humans use their hands for exploring and interacting with the world around them, dogs use their mouths to do the same.
Similarly to barking and digging, chewing is a natural behavior in dogs, but can pose a problem when it's destructive. A dog's excessive chewing behavior may be caused by medical problems or separation anxiety. When this occurs, a veterinarian or dog behaviorist may need to be consulted.
If your dog likes chewing, make sure he has access to a wide range of interesting and tasty chew toys. Discourage your dog from chewing on wires, cords, papers, or anything else he may have been using as an inappropriate chewing outlet.
Nevertheless, you might still find that your dog is bored or under-exercised if he keeps chewing the wrong things.