Most people have occasional obsessive thoughts or compulsive behaviors. In an obsessive-compulsive disorder, however, these symptoms generally last more than an hour each day and interfere with daily life.
Obsessions: are intrusive, irrational thoughts or impulses that repeatedly occur. People with these disorders know these thoughts are irrational but are afraid that somehow they might be true. These thoughts and impulses are upsetting, and people may try to ignore or suppress them.
Examples of obsessions include:
Thoughts about harming or having harmed someone
Doubts about having done something right, like turning off the stove or locking a door
Unpleasant sexual images
Fears of saying or shouting inappropriate things in public
Compulsions: are repetitive acts that temporarily relieve the stress brought on by an obsession. People with these disorders know that these rituals don't make sense but feel they must perform them to relieve the anxiety and, in some cases, to prevent something bad from happening. Like obsessions, people may try not to perform compulsive acts but feel forced to do so to relieve anxiety.
Examples of compulsions include:
Hand washing due to a fear of germs
Counting and recounting money because a person
can't be sure they added correctly
Checking to see if a door is locked or the stove is off
"Mental checking" that goes with intrusive thoughts
is also a form of compulsion