It consists of presence of obsession of thoughts and compulsion to act upon it.
It has recurrent or impulsive thoughts in mind about contamination or confusion.
Here thoughts/urges/impulses leads to some action or compulsions.
Compulsive behavior can be like repeating washing of hands, checking of latch or door, praying or counting.
In children reparation of words while reading can be seen.
This act are done to reduce anxiety or distress.