Although wolves do bark (or more accurately, howl or bay), they do so only in specific situations. According to Coppinger and Feinstein, dogs bark in long, rhythmic stanzas but adult wolf barks tend to be brief and isolated. Compared to wolves, dogs bark frequently and in many different situations.

It has been suggested that the reason for the difference lies in the dog's domestication by humans. Dogs present a striking example of neoteny, the retention of juvenile characteristics in the adults. They are similar to young wolves in many of their mannerisms and physical features, such as large heads, flat faces, large eyes, submissiveness and vocalizing – all of which are exhibited in wolf puppies.

Some believe that these characteristics were deliberately selected soon after domestication. There may have been a number of reasons for this. For instance, an overgrown puppy would very likely have been seen as a more engaging companion than a more mature but less amusing pet, as well as being less aggressive. More prosaically, an increased tendency to bark could have been useful to humans to provide an early warning system. Dogs may have been used to alert their owners that another unfamiliar band of humans or a predatory animal was in the area.

Individual dogs bark for a variety of reasons. They may bark to attract attention, to communicate a message, or to express excitement. Dog barks do not constitute an information-rich message in the same fashion as human speech, but they do nonetheless constitute more than mere noise. Statistical analysis has revealed that barks can be divided into different subtypes based on context and that individual dogs can be identified by their barks. Disturbance barks tend to be harsh, low frequency, and unmodulated, whereas isolation and play barks tend to be tonal, higher frequency, and modulated. Barks are often accompanied by body movements as part of a broader package of dog communication.

Canine barking can be a nuisance to neighbors, and is a common problem dog owners or their neighbors may face. It is important to realize that a dog which barks is attempting to communicate something, be it anxiety, discomfort, friendliness, assertiveness, loneliness, warning, alarm, deterrent, or other meanings. Different kinds of barking often require different kinds of approach to reduction.

Common approaches are as follows:

1. Attempt to understand the cause. Know what triggers the barking. Treat any causes which can be treated.
2. Use positive training methods to correct the behavior. Dogs are more likely to bark from anxiety or stress, than otherwise, so punishment can often cause problems by reinforcing a cycle of bad behavior. Instead consider:
   • Repeated exposure - to strangers or telephone rings (the "stimulus"), whilst you calm the dog and persuade it to remain quiet
   • Distraction - as the stimulus happens, offer treats, give praise, do something to take the dog's mind off it or an alternate preferred behavior.
   • Reshaping - use clicker training (a form of operant conditioning) or other means to obtain barking behavior on command, and then shape that control to give you control over silence too.
3. Seek professional dog trainer advice