Compulsive checking, contamination or mental contamination, symmetry and order and Hoarding are different types of obsessive-compulsive disorder. In Checking type disorder, the patient always has a need for checking cars, water taps, gas or electric stove cobs, house lights and candles, emails and letters, etc for reassurance. This can sometimes damage that particular object.
Another type of observational worry is observed in mental contamination where a patient has thought of contamination. Due to this, the patient can harm themselves or their loved ones. In symmetry and order, a patient will always try to keep everything perfect and symmetrical. In hoarding OCD, people avoid discarding useless things and worn-out possessions.