A backorder occurs when a customer places an order for a product that is currently out of stock. This means the item is not available for immediate shipment, but the seller expects to receive more inventory soon. Customers are often informed about the estimated delivery time for backordered items. When a product is on backorder, it allows businesses to continue taking orders even when supplies are low. This practice helps maintain customer interest and can lead to increased sales once the item becomes available. Companies often communicate updates to customers regarding their backordered items to keep them informed.