Backlog

A backlog is the pile-up of work, orders or transactions that have been received but not yet completed. In business, a backlog of signed customer orders is often reported as an indicator of future revenue, especially by manufacturers, defence contractors and software firms, where it is sometimes called the order book or remaining performance obligations under revenue recognition rules. A growing backlog can signal strong demand, but it can also point to capacity limits or supply problems. In operations, the term covers anything waiting in a queue, such as unprocessed payments or an alert backlog in compliance teams. On crypto networks, a backlog of unconfirmed transactions builds up in the mempool when demand for block space exceeds supply. Also see Backorder and Bottleneck.