A back order is a customer order that has not been fulfilled. A back order generally indicates that customer demand for a product or service exceeds a company's capacity to supply it. Total back orders, also known as backlog, may be expressed in terms of units or dollar amount.
Companies have to walk a fine line in managing their back orders. While consistently high levels of back orders indicate healthy demand for a company's product or service, there is also a risk that customers will cancel their orders if the waiting period for delivery is too long. This is less of a risk for innovative products with strong brand recognition in areas such as technology.