A queue consists of a number of packets. These packets are bound to be routed over the network, lined up in a sequential way with a changing header and trailer and taken out of the queue for transmission by a network device using some defined packet processing algorithm like first in first out (FIFO), last in last out (LIFO), etc. The queue dequeues, or takes out a data packet from the head, when it needs to transfer and trailer by adding new data packets to the queue, which is known as enqueuing.
A queue works almost on the same methodology used at banks or supermarkets, where the customer is treated according to its arrival. An example would be FIFO or some other priority if they are a privileged customer. Similarly, a network queue processes data packets based on their arrival, priority, smallest task first and multitasking, FIFO, LIFO, emption and pre-emption.
This definition was written in the context of Networking