People of obsessive-compulsive disorder are often troubled by obsessive thoughts and compulsive behaviours, causing distress in their everyday lives. Examples of obsessions/compulsions include excessive handwashing, constantly collecting things that are not needed, repeatedly checking to see if windows, doors or gas outlets are closed etc. Effective treatments help them to address the obsessive thoughts and compulsive behaviours, as well as the underlying issues driving these thoughts and behaviours.