queues learning objective queue is an important data structure which is extensively used in computer applications in this we will study the operations that can be performed on queue the will also discuss the implementation of queue by using both arrays as well as linked lists the will illustrate different types of queues like multiple queuesdouble ended queuescircular queuesand priority queues the also lists some real-world applications of queues introduction let us explain the concept of queues using the analogies given below people moving on an escalator the people who got on the escalator first will be the first one to step out of it people waiting for bus the first person standing in the line will be the first one to get into the bus people standing outside the ticketing window of cinema hall the first person in the line will get the ticket first and thus will be the first one to move out of it luggage kept on conveyor belts the bag which was placed first will be the first to come out at the other end cars lined at toll bridge the first car to reach the bridge will be the first to leave in all these exampleswe see that the element at the first position is served first same is the case with queue data structure queue is fifo (first-infirst-outdata structure in which the element that is inserted first is the first one to be taken out the elements in queue are added at one end called the rear and removed from the other end called the front queues can be implemented by using either arrays or linked lists in this sectionwe will see how queues are implemented using each of these data structures