Dog Obedience Advice is a free resource offering advice on dog training and a host of common problems dog owners face, including: aggression in all its forms, from territoriality to possessiveness, and from dominance aggression to aggression caused by fear; the most common and frustrating obedience issues, such as problem digging, chewing, and barking; and comprehensive information on house training methods with sound advice on tackling all of the most common housebreaking problems.
1. To assert dominance. Whether it's jumping on people or jumping on furniture, both instances illustrate a dog that wants to raise his station in life. By jumping on you or jumping on the couch, he's saying that he's the pack leader--something that you DON'T want to happen, as a dominant dog is much more difficult to train (and can become quite aggressive). In either case, you'll definitely want to institute the proper alpha dog training techniques, if you haven't already.