In the United States, Canada, and Europe, some bakeries, grocery stores, or restaurants will routinely donate food according to a Good Samaritan Food Donation Act, but more often, because of health laws or company policy, they are required to discard food items by the expiration date, because of overstock, being overly ripened, spoiled, cosmetically imperfect, or blemished. If disposed of “as is” and not destroyed, some of this food may be made “safer” for consumption if properly decontaminated and spoiled ruminates are removed. Otherwise, it is quite possible food poisoning will result from eating dumpster food, especially if it is not cooked/recooked afterwards.

Offices, factories, department stores, and other commercial establishments also may throw out nonperishable items that are irregular, were returned, have minor damages, or are replaced by newer inventory. Generally, the more perishable and inexpensive the item, the more likely that it will be disposed of intact. Otherwise, most items tend to be in such a state of disrepair or cosmetically flawed that they will require some work by the dumpster diver to make the items functionally usable. A general tenet found among seasoned Dumpster Divers is to avoid returning items (for money/exchange) through the front door that were tossed out the back door. Stores who even suspect this has happened will take steps to ensure it ceases, thus ruining future diving.

Residential buildings tend to throw away very little usable food or “new” items that could not be sold, but sometimes are a good source of clothing, furniture, appliances, and other housewares. Because some people find it easier to dispose of an item rather than donating or recycling, the dumpster diver tends to be the only reprieve for items being buried in landfill.

Some consumer electronics are dumped because of their rapid depreciation, obsolescence, cost to repair, or expense to upgrade. Owners of functional computers may find it easier to dump them rather than donate because many non-profits and schools are unable or unwilling to work with used equipment.^[3] Some organizations like Geeks Into The Streets, reBOOT, Free Geek and Computerbank try to refurbish old computers for charity or educational use.

-Wikipedia