Phobias are an irrational and extreme fear of a distinct object, activity, or situation. Examples of specific phobias include fear of tight spaces (claustrophobia), spiders (arachnophobia), dogs (cynophobia), or leaving the house (agoraphobia). Specific phobias are among the most common anxiety disorders, affecting about 5–10 percent of the population. Phobias tend not to get better on their own and require mental health professional help. Most people with phobias respond well to psychiatric and psychological treatment.