Hoarding disorder is a mental illness that impacts 2-6% of the population. Hoarders have difficulty disposing of things that they don't need. Hoarders also keep large quantities of items that most people would consider to be of little value, such as newspapers, old clothing, household goods, and plastic bags. Some hoarders also suffer from compulsive buying and collection of free stuff, such as fliers. This behavior affects the person emotionally and socially.