One thing we know and there is no doubt about is that a dog will bark at some point. Whether it is rare occurrence or regular occurrence, it will happen without question. Some will be extremely loud and others quite soft and maybe even cute at times, and along with the variety in noise level there will be a variety in the situations as well.
Barking can be of three main categories:
In terms of environmental this is basically any of their surrounding. It can be a territorial issue with a person or another animal coming in what they consider their space and can trigger barking. It can get louder and more excessive, the closer the perceived threat gets. The dog will usually get aggressive in this situation and extremely alert to the situation. It is for this reason many dogs were kept in the past simple for protection of properties.
Environmental can also be other things, such as weather, a noisy party going on nearby, a loud car or something even like fireworks. In most cases it should not be anything to worry too much and the barking will be over pretty soon as soon as they realise it is not much of an issue. If it does persist then perhaps speak to an expert.
Emotional triggers can be anything such as happiness, fear, boredom, loneliness etc. Often times it is their way of seeking a bit of attention. Dogs are a social animal and love company and can get bored easily. So respond in a positive manner rather than ignoring. Try to keep them on their paws and stimulated with activities and things to do, as a bored dog can be very disruptive.
Barking for physical needs is anther category. All these categories can overlap to a certain extent, here we are talking about the dog barking for a physical need. This could be because they are hungry or thirsty or want to go out for a walk. Perhaps you have a regular walking schedule and suddenly one day you get busy and may find the dog barking asking to be let out for a walk. Here the barking is not necessarily bad and the dog can be perfectly happy. It can just be difficult to decipher the need if you have not spent much time together. After a while you will pick up on the signals and understand the reasons for the barking a lot more.
Just remember dogs are incredibly smart animals and do not just bark without cause or reason. So learn to understand them and in time it will help create a more powerful bond. You will get to know their emotions and connect on a whole different level.