All dogs bark sometimes. It is their primary mode of communication but when a dog barks excessively it is annoying for everyone. Some breeds bark more than others but all dogs bark at times.
Dogs will bark excessively for a few reasons. If your dog spends the entire day in the house or in the same yard he may be barking excessively because he is bored. Dogs love exercise and interacting with people. Dogs also love social stimulation, as they are pack animals. If your dog is barking out of boredom try going on more walks or incorporating more playtimes throughout the day
Dogs often bark when they feel nervous or scared. Some dogs are never properly socialized and therefore the slightest thing can frighten them. While you are training your dog take him to many different places and have him be around a variety of people. Reward him when he is quiet and well behaved. A food treat will do wonders to keep him contained in different places and different situations. Soon he will start associating being quiet and well behaved with the treat and this will work amazingly well towards his excessive barking under these conditions.
Dogs will bark when they are wanting something from you. However, while you need your dog to communicate with you, you also do not want this type of barking to become a bad habit. If you always respond to his barking he will always continue to bark. Try to get him to communicate with you in different ways by rewarding and praising him for different behaviors. Otherwise you are just training him to bark.
Sometimes your dog will bark excessively because you have left home and you are not with him. This barking from separation anxiety is disturbing to the neighbors and others so it is wise to try to eliminate it. Start when he is a puppy and crate him when you leave so he learns to be happy in his own space. Also never make a big deal out of leaving home but rather just sneak away quietly. He may never know that you are gone and if he does he will not be so loud about it.
Dogs bark to protect you and there are situations when we all would appreciate that. However, every single day when the mailman or mail person! delivers the mail is not one of those times! This is atime when socialization and training can really pay dividends. Take your dog to meet the mailman, let them become acquainted and hopefully your dog will not bark at him everyday. Another way to get him to stop barking at inappropriate times is to distract him with a toy or a treat. But when your dog barks to protect you remember that there may come a situation when you will appreciate that so limit your training to people you know.
A professional dog trainer can offer you some tips and techniques to curb excessive barking but oftentimes just more socialization and more playtimes will curb the excessive barking. The one thing you should consider though is that your dog is usually barking for a reason and you should find out what that reason is. Then you can deal with the barking.
Dogs who only bark at proper times are much less annoying than dogs that bark excessively. Start training your dog away from excessive barking while he is still a pup and when he is all grown up you will know when he barks he has a good reason.