There are two main forms of Obsessive-Compulsive Disorders: you can suffer from both obsessions and compulsions, or just one of either. Obsessions are annoying, unwelcome thoughts, ideas or urges that repeatedly appear in your mind. For example: thinking that somebody could die, or that you could have been contaminated by dirt or germs. Compulsions are repetitive activities you have to do against your will, such as: washing hands, checking if a door is locked etc.