Obsessions are unwanted thoughts, images, or sensations that occur repeatedly. The content of the obsessions are often frightening, gives you the feeling that something bad will happen, and leads to intense anxiety, discomfort, and fear. Essentially, it is equivalent to having a nightmare that keeps replaying in your mind like a broken record.
On the other hand, compulsions are physical or mental reactions performed to keep the bad feelings from happening. They can also provide escape from the unpleasant feeling or let you feel safe temporarily. They often feel like habits that take up an excessive amount of time. The problem is that the relief you gain after a compulsion is short-lived until the obsession returns. In time, this bond becomes stronger and more difficult to break as it develops into a vicious cycle of obsessions with corresponding compulsions.
About 1 in 100 adults in the US, and at least 1 in 200 children and adolescents are currently suffering from OCD. However, many more are undiagnosed and suffering quietly due to shame, embarrassment, or simply a lack of awareness. OCD usually begins in childhood or adolescence. It does not discriminate and can happen to anyone.