Obsessive-compulsive disorder, or OCD, is made up of two different parts: obsessions and compulsions. On one hand, obsessions are unwanted thoughts, ideas or urges that are distressing to you. They may seem very strange or have to do with things you would not normally think about doing.
A diagnosis of OCD requires the presence of obsessions and/or compulsions that are time-consuming, cause major distress and impair work, social or other important areas of functioning. Many people who have been diagnosed with obsessive-compulsive disorder will have persistent and the unwanted thoughts. They may also have routines and behaviours that are rigid, and not doing them causes great distress for the individual.
Some examples of compulsions:
Cleaning to reduce the fear that germs, dirt, or chemicals will "contaminate" them. Some people spend many hours cleaning themselves or their surroundings.
Checking to reduce the fear of harming oneself or others by, for example, forgetting to lock the door or to turn off the stove. Some people repeatedly retrace driving routes to be sure they haven’t hit anyone.