Hoarding occurs when we retain more possessions than we require. When the retention of these possessions start to cause some discomfort the issue can be seen as a diagnosable mental health issue.
We all have too much stuff. It is the degree and type that defines is a problem is present. People who are collectors typically collect a specific category such as artwork, postcards, clocks etc. The collector typically experiences pleasure at the time of purchase and during the period the possession is held. A person with a hoarding disorder experiences pleasure during the purchase but the holding of an item may have a conflicted feeling where retention may be a burden but yet be unable to let it go due to a sense of obligation, commitment and responsibility.
Research shows that a conservative 2% of the population have some hoarding issues.