Barking is a very normal behavior for dogs. Barking is a way for a dog to communicate something. He may be insecure, alert, being demanding, alone, or even in pain. The important part to keep in mind is the WHY. That is what needs to be addressed. Barking can be considered a "symptom" of something else.
The first step in changing your dogs behavior is to address the symptom behind his bark. If he is nervous around other dogs, you will want to slowly expose him to other dogs at a distance he can happily take food rewards and praise (read Dog To Dog Reactivity). If he starts to bark, you are too close to the other dog, and you should step a few feet back. If your dog barks at someone passing by your house, calmly say your dogs name and ask him to return to you for a reward (read Barking At Windows). Dont worry, you will be rewarding him for coming to you, not barking. If done regularly, your dog will anticipate you asking him to come to you, and will start to come automatically when someone passes the house.
Yes, a little training can go a long ways in curbing excess barking. If your dog is demand barking (wanting you to pet him, throw the ball, feed him), then the best way to stop that behavior is not to do those things when hes barking (read Polite Dog Feeding Routine). It will take some time for his barking to stop since he learned in the past it worked, so hang in there. It may even get worse at first, like a temper tantrum.
Addressing the symptom of your dogs barking (separation anxiety, stress, boredom) is the only way to have a calm, well-behaved dog. If you have a chatty Cathy, expect a little work in the beginning, but a peaceful end. Good luck.
Check out my live demonstration on how to curb your dogs barking!