Obsessive-Compulsive Disorder (OCD) is a common, chronic, and long-lasting disorder in which a person has uncontrollable, reoccurring thoughts (obsessions) and/or behaviors (compulsions) and feels the urge to repeat them over and over. These symptoms can interfere with all aspects of one’s life, such as work, school, and personal relationships.
Obsessions are repeated thoughts, urges, or mental images that cause anxiety and compulsions are repetitive behaviors that a person with OCD feels the urge to do in response to an obsessive thought.
Now, not all rituals or habits are compulsions. Everyone double checks things every now and then which is a normal thing to do. A person with OCD generally can't control their thoughts or behaviors, even when those thoughts or behaviors are recognized as excessive. These people may also experience significant problems in their daily life due to these thoughts and or behaviors.
Common examples of obsessions and compulsions are: