Dogs are actually descended from wolves, and although the modern dog is much cuddlier nowadays than his wild ancestor, Fido still has some wolf-like characteristics, including his sharp hearing, keen sense of smell and instinctive need to be part of a pack. Never forget that, to your dog, you and everyone else in your household are part of his pack.
A pack has one leader - someone who bosses everybody else around and is respected by all the other members. Your dog knows that somebody's got to fill that top dog position at all times, in case your group get attacked by another pack; normally he’ll be happy to leave that top spot for you, but if you’re not ready to step up and take that job yourself, then he’ll have no choice but to do it. Don’t give him that chance, or you’ll have a world of behavioral problems on your hands. Make sure you’re unquestionably the top dog – for your own peace of mind and for Fido’s as well.