Vocalization bark is more usual to produce the dog, although it has a large repertoire of audio signals. Normally bark to get nervous or excited before something unknown happens in their environment, for example, when a stranger comes to the home in which he lives. Therefore, the barking is a sign for the owner of a potential danger that the dog can alert.
However, it is also a form of communication between dogs and even there who says they have developed a real language to talk to each other. The truth is that the barking is the main weapon that has to communicate with their masters.
The meaning – The wolf dog proceeds, originally growing up in the woods, where sound messages are useful because of the difficulty that causes thick vegetation to communicate visually.
The main cause of barking is the presence of strangers, both men know the dog or other dogs. By this vocalization, the animal intended to effect protection of its territory. Therefore, man has used the dog for many years, as a symbol of alarm about possible dangers. This domestication and genetic selection has humans, has caused the dog to bark much more frequently than the wolf.
But there are other causes that can cause the dog barking, for example during the game or just to attract attention from their owners. In many cases, especially when due to the presence of strangers, barking is an aggressive gesture or challenging, but not always. When accompanied with other aggressive attitudes, such as body position.