A phobia is an irrational and strong fear of something. Phobias can develop for many reasons and make everyday activities difficult. In severe cases, phobias can lead to disorders like obsessive compulsive disorder (OCD) which involves unwanted thoughts and irresistible urges to perform rituals. Both OCD and panic disorder, which involves episodes of intense fear, can affect people's personal lives, relationships, jobs, and travel. The most effective treatments are medication and behavior therapy which involves gradual exposure to fears.