Self storage (a shorthand for "self-service storage", and also known as "mini storage") is an industry in which storage space (such as rooms, lockers, containers, and/or outdoor space) is rented to tenants, usually on a short-term basis (often month-to-month).
Self-storage tenants include businesses and individuals.
The self-storage industry is primarily a United States-based industry: of the 58,000 storage facilities worldwide in 2009, 46,000 were located in the United States. In 2007, the U.S. self-storage renting and leasing market was nearly $6.6 billion. 
Self-storage facilities rent space on a short-term basis (often month-to-month, though options for longer-term leases are available) to individuals (usually storing household goods; nearly all jurisdictions prohibit the space from being used as a residence) or to businesses (usually storing excess inventory or archived records). Some facilities offer boxes, locks, and packaging supplies for sale to assist tenants in packing and safekeeping their goods, and may also offer truck rentals (or may allow free use of a truck for a new tenant).
Items are generally not covered by the facility's insurance; the lessor may be covered by his/her own insurance policy (if such policy has coverage for items stored off the premises of the insured) or may purchase insurance to cover the items (which the facility may offer as a service through a third-party carrier, and in some cases may require the lessor to purchase as a condition of rental).
The rented spaces are secured by the tenant's own lock and key. Unlike in a warehouse, self-storage facility employees do not have casual access to the contents of the space (and, thus, the facility is generally not liable for theft). A self-storage facility does not take possession or control of the contents of the space unless a lien is imposed for non-payment of rent, or if the unit is not locked the facility may lock the unit until the tenant provides his/her own lock.
Although there is historical evidence of publicly available storage in ancient China, modern self-storage facilities (in which the tenant has exclusive access to the storage space) did not begin to appear until 1958, when Lauderdale Storage in Fort Lauderdale, Florida (founded by the Collum family) opened for business.
Modern storage facilities grew slowly through the 90s, at which time demand outpaced supply and caused a rush of new self-storage developments. From 2000 to 2005, over 3,000 new facilities were built every year.
Self storage today
At year-end 2009, a total of some 58,000 self-storage facilities, owned by 30,235 companies, have been developed in the United States on industrial and commercial land parcels. There is more than 2.35 billion square feet of self-storage in the U.S., or a land area equivalent to three times Manhattan Island under roof. The five large publicly traded storage operators (four REITs and U-Haul) own or operate approximately 9% of self-storage facilities. More recently, in many metropolitan cities where competition among storage companies is fierce, better parcels of land near residential and commercial areas are being converted into self-storage once approved by zoning panels.
Self-storage businesses lease a variety of unit sizes to residential and business customer/tenants. Popular unit sizes include 10x5 (10 feet wide by 5 feet (1.5 m) deep) which is about the size of a large walk-in closet, 10x10 (the size of a child's bedroom), 10x20 (one-car garage), 15x20 and 20x20 (two-car garage). The storage units are typically window-less, walled with corrugated metal, and lockable by the renter. Each unit is usually accessed by opening a roll-up metal door, which is usually about the same size as a one-car garage door (smaller units may be accessed by a hinged metal door). A controlled access facility may employ security guards, security cameras, individual unit door alarms and some means of electronic gate access such as a keypad or proximity card. A few facilities even use biometric thumbprint or hand scanners to ensure that access is granted only to those that rent. Self-storage facility operators frequently provide 24-hour access, climate controlled storage, outdoor storage for RVs and boats, and lights or power outlets inside the storage unit as amenities to set themselves apart from competitors.
In rural and suburban areas most facilities contain multiple single-story buildings with mostly drive-up units which have natural ventilation but are not climate-controlled. These buildings are referred to as "traditional" storage facilities. Climate-controlled interior units are becoming more popular in suburban areas. In urban areas many facilities have multi-story buildings using elevators or freight lifts to move the goods to the upper floors. These facilities are often climate-controlled since they are comprised mostly, if not totally, of interior units. Warehouses or grocery stores are sometimes converted into self-storage facilities. Loading docks are sometimes provided on the ground floor. Also, complimentary rolling carts or moving dollies are sometimes provided to help the customers carry items to their units. Urban self-storage facilities might contain only a few floors in a much larger building; there are successful self-storage businesses co-located with manufacturing plants, office tenants and even public schools.
One in ten U.S. households now rent a self-storage unit. The growing demand for self-storage in the U.S. is created by people moving (some 40 million people move each year according to U.S. Census data), and by various lifestyle transitions, such as marriage, divorce, retirement, a death in the family, etc. Recent surveys of self-storage companies indicate a positive trend in market demand and occupancy rate.
Over 50,000 self storage facilities currently exist in the U.S.  ranging from companies with a nationwide presence to companies with regional footprints or even stand-alone independent "mom and pop" facilities.
Self storage worldwide
Self-storage or variations on the business model are now found in many parts of the world. According to a report (1 June 2006) by Mintel Consulting and in collaboration with the Self Storage Association of the United Kingdom space available for rental in the USA is approximately 1.6 billion rentable square feet, against 22 million rentable square feet in Australia and around 20 million in the United Kingdom. The report also states that there are around 50,000 facilities in the USA, 1,000 in Australia, around 800 in the United Kingdom, 100 in Germany and 380 in France. In 2013, the BBC reported that the United Kingdom had around 1,000 facilities with a combined floorspace of over 30,000,000 square feet (2,800,000 m2), and that self-storage sites were increasingly popular bases from which to run small businesses.
In the United States, self-storage facilities may hold storage auctions or lien sales to vacate non-paying tenants according to their enforcement rights that are outlined within the lien law of each jurisdiction. Facilities owners are required to give public notice of the sale or auction in a printed periodical in most states, while other states are considering allowing public notice of sales to be done in the internet. However, a tenant in lien has the right to pay their outstanding bill until the moment the auction begins and thus reclaim his/her items; those units would be removed from the auction (which, in some cases, may result in the entire auction being cancelled).
These auctions/sales are open to the general public, with most bidders buying for the purpose of reselling for profit. Usually the terms of sale are cash-only. Once the auction for a unit starts, the door to the unit is opened and potential bidders are allowed to view the contents only by looking in from the doorway; they may not step inside, touch, or move any of the contents prior to the auction. The spaces are usually sold "as is". The purchaser of a unit receives everything in it (treasure and trash) and is responsible for removing the contents within a given time frame (usually a day or two, though a facility may allow a purchaser to subsequently rent the unit; the facility may also charge a cleaning deposit to be refunded once the unit is cleaned and made available to the facility). In some jurisdictions, the storage facility may confiscate controlled items (such as firearms) if they are immediately visible.
In the fall of 2010, two new television programs featuring storage auctions, Storage Wars and Auction Hunters were released. The popularity led to additional shows such as Storage Hunters, Storage Wars: Texas, and Storage Wars: New York which helped increase the visibility and interest of storage auctions. Storage Wars: Canada also debuted on the Outdoor Living Network in 2013.
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