A pre-order is an order placed for an item which has not yet been released. The idea for pre-orders came when people found it hard to get popular items in stores due to their popularity. Companies then had the idea to allow customers to reserve their own personal copy, before the release, which has been a huge success. Pre-orders allow consumers to guarantee immediate shipment on release, manufacturers can gauge how much demand there will be and hence the size of initial production runs, and sellers can be assured of minimum sales. Additionally, high pre-order rates can be used to further increase sales.