OCD can take many forms and can be likened to a phobia in that the person suffering with it will do all they can to avoid whatever it is that causes them discomfort or anxiety. One aspect in which it differs from a phobia is that OCD takes over people's lives, spreading beyond the initial habit to encompass many areas of life. 

 

At its inception, OCD can begin as a fear of doing or not doing something. Out of this can grow a ritual that needs to be carried out in order to avoid or prevent a dreaded consequence. Any interruption to or incompletion of this ritual or habit creates intense anxiety, often accompanied by intrusive thoughts.