Hoarding behavior, or disposophobia, is the compulsive drive to keep things that aren't needed or that should be thrown away. Many hoarders live in homes with the majority of the living space crammed with a mess of different items. The exact things that hoarders keep piling up in their homes varies, but many of them won't throw out perishable products way past their expiration date or even vegetable peels and food wrappers. The main aspects of hoarding behavior are constantly acquiring new possessions and not discarding any old items.
The exact behaviors and attitudes involved in hoarding vary depending on the individual. For example, some hoarders have the mindset that they are "rescuing" things that need to be saved, while others realize what they are doing but still can't control their hoarding behavior. These hoarders may feel extremely embarrassed about their compulsion to fill their home up with piles of garbage or non-meaningful items not needed for daily living. Professional mental help is often necessary to overcome compulsive hoarding.
What makes hoarding behavior distinct from disorganization or sloppiness is the strong compulsion to acquire things, especially items considered as garbage. Hoarders don't usually carefully collect certain items to display, but rather pile up many different types of things into their homes on a regular basis, whether they have room or not. There are some hoarders who may focus on items made of the same material, such as metal, but they usually have delusions that the substance is valuable. For instance, they may adamantly assert that tin foil pie plates are actually sterling silver or that old daily newspapers will become valuable someday. Some hoarders are neater than others in their attempts to neatly stack all of the items they keep in their homes, but typically at some point this fails, as hardly any space becomes left to even walk comfortably through rooms.
Interference with daily living such as cooking, bathing and sleeping, as well as difficulty in social relationships are common consequences hoarders face for acquiring an excess of clutter. A hoarder may form successful relationships with others, but at some point is likely to become faced with confessing to hoarding behavior as people won't understand why they aren't ever invited to his or her home. As hoarding behavior often includes not returning borrowed items, this tends to result in friction with neighbors, friends or family. Loved ones also worry about rats, cockroaches and unsafe conditions; if the hoarding problem is severe, the hoarder may be in danger of losing his or her home at least temporarily if it's condemned by a local health department.