The main characteristic of phobias is the elevated, disproportionate fear response to a certain situation or object.
The person experiences a high-intensity emotional reaction that is accompanied by high discomfort when faced with said object or situation because they consider that the event has characteristics that can endanger their integrity. Faced with such danger, the person reacts by fleeing or avoiding being exposed to the stimulus (i.e. the feared object or situation).
When the person is away from the phobic element, they may still present fear due to apprehension or anxious expectation of a possible new encounter with the feared element.
Despite the high prevalence of phobias, compared to other anxiety disorders, it is unusual to seek for help and go to therapy to stop having this experience. What often happens is that the person will develop strategies to avoid the feared stimulus very easily and will ask for help only when there is no other option.
The good news is when the person goes to therapy, cognitive behavioral therapy is very efficient in helping with phobias.
Two examples of specific phobias are agoraphobia (i.e. fear of scenarios where immediate aid is unlikely) and selective mutism (i.e. inability to speak in specific situations).