queued

Queued is the past participle of the verb queue and, in general usage, describes something that has been placed in a line or sequence to be processed. The verb queue means to form such a line, and the noun queue refers to the line itself. In computing and information systems, items are often described as queued when they are waiting their turn for service.

In computer science, a queue is a linear data structure that stores elements in a sequence for orderly processing. Elements are typically removed in FIFO order, meaning the first item added is the first to be processed. Some queue implementations support priority levels or multiple priority queues, which can alter processing order.

Queued items are common in various domains. In operating systems, processes and I/O requests may reside in ready queues or device queues until the scheduler or device becomes available. Print spooling, task scheduling, network packet buffering, and message queuing systems also use queues to manage work that cannot be processed immediately.

Queueing theory studies waiting lines and performance characteristics of queues. Models specify arrival rates, service rates, and queue capacity to estimate metrics such as average wait time, system utilization, and queue length. It informs design of systems from call centers to computer networks.

The term has different connotations in British English (to queue up) and American usage, but the adjective form queued is common in computing and IT contexts to indicate that an item is awaiting processing.