A dog's bark is a really interesting phenomenon. Did you know that wild dogs do not bark? Neither do wolves. They make a sort of woofing sound, but it's not the loud bark of the domestic dog as we know it. If a domestic dog turns feral, he will eventually stop barking. If the same dog is recaptured and redomesticated, he will start barking again. Ethologists, scientists who study animal behavior, speculate that the bark of the domestic dog is a form of communication which is evidently unneccessary in the wild. So, the next time your dog barks, consider what he is trying to communicate.

Dogs bark, ducks quack...

Some dogs have been selectively bred to bark in certain instances. The best trait of a good watchdog is that he gives warning barks when someone is approaching the home. Dogs may bark to communicate a need. It's good when a dog barks to let you know he needs to go outside to use the bathroom. They may also bark to communicate other things, such as warning someone to back off, or I'll bite! This is good, too. As the proverb says, a barking dog isn't biting. Dogs may bark to get your attention and ask you to play with them or feed them. They can get so excited while playing that they bark in exuberance. They may also bark out of boredom or pain.

Shut up, already!

Barking is normal, but it can quickly become a nuisance. Few things will make your neighbor hate you faster than an excessively barking dog. To figure out how to stop excessive barking, you first have to determine the cause of the barking. The barking is only a symptom. Find the cause to find a cure.

Territorial/Watchdog
Let your dog bark to warn you that someone is coming. Then, tell him Thank you, and that's enough. Teach him that once you have acknowledged his warning, he should stop barking. One way to do this is to establish the Quiet command. You will have more success if you teach this in practice situations rather than trying to teach it when someone actually is approaching your home. Once he understands the Quiet command, use it to end exuberant barking at visitors. Let him bark 2 or 3 times, then issue the Quiet command. Praise and reward.

Boredom
If your dog is barking barking barking at nothing in particular, he is likely bored. Give him something go do. Take him for a walk. Play a game of fetch. Teach him a neat trick that will impress your friends. Give him an interactive toy such as a Buster Cube or a stuffed Kong.

Playing
If your dog gets so excited during play that he just can't stop barking, stop the playing briefly to let him calm down. You might not want to use your Quiet command here because he could be too excited to follow it, and it could break down the effectiveness of the command when you need it. Instead, use a noise to get his attention, such as "ECK!" or "SHHH!". That should get him to stop and take a breath and calm himself a little. If not, stop the play for a few minutes before letting him resume.

Attention
If your dog is using barking to manipulate you into doing what he wants, stop letting him push you around. Dogs do what works. If barking at you works to get you to throw his ball for him or pet him, he will keep doing it. If you want that to stop, you have to ignore the barking and not give him what he wants. Do not hold out for a while and then give in after he has barked at you for several minutes. This will only teach him to bark MORE. He will learn that if he just barks long enough, you will eventually cave and give him what he wants. You have to outlast him. You can do it!

Warning
If your dog is barking to warn others to back off, he is likely afraid. Work on building his confidence. Obedience training is an excellent way to do this. Also, happy dogs are not overly fearful dogs. Finally, consider if this is an aggression problem.

Anxiety
Excessive barking can be a nervous habit due to anxiety. Ease your dog's anxiety to end the barking.

Additional Resources

Barking Ethology

Bark! Bark! Bark!

Noise & Neighbors