Priority Queues:- 

There are some queues in which we can insert items or delete items from any position based on some property. Now, those queues based on the property of priority of the task to be processed are referred to as priority queues. 

To implement a priority queue we first need to identify different levels of priority and categorize them as the least priority through the most priority level. After having identified the different levels of priority required, we then need to classify each incoming item (job) as to what priority level should be assigned to it. While creating the queues, we need to create n queues if there are n priority levels defined initially. Let suppose there are three priority levels identified as P1, P2, and P3. In this case we would create three queues as Q1, Q2 and Q3 each representing priority levels P1, P2, and P3 respectively. Now every job would have a priority level assigned to them. Jobs with priority level as P1 will be inserted in Q1. Jobs with priority level P2 are inserted in Q2 and so on. 

 Each queue will follow FIFO behavior strictly. Jobs are always removed from the front end of any queue. Elements in the queue Q2 are removed only when Q1 is empty and the elements of the queue Q3 are only removed when Q2 is empty and so on.