Obsessive Compulsive Disorder (or OCD) is a mental disorder characterized by unwanted feelings, thoughts, and behaviors. With OCD the sufferer will experience an obsession and then perform some kind of ritual such as checking the stove to make sure that it is turned off over and over again to relieve their anxiety.
The exact cause of OCD is not known, though it seems to be biological.
A famous example of someone who suffered from OCD was Howard Hughes. Hughes got so bad that he wouldn't see anyone. He would just sit around naked and watch movies. For more information on Howard Hughes, visit Wikipedia.
One man had OCD so bad his rolls of toilet paper had to be fixed just right.
Let's look at some of the most common symptoms of OCD:
Frequent hand washing.
Fear of germs.
Getting upset when things are out of order.
Recurring sexual thoughts that you don't want or like.