A priority queue is a specialized data structure that extends the functionality of a regular queue by associating a priority level with each element. In a regular queue, elements are processed in the order they arrive, following the first-in, first-out (FIFO) principle. In contrast, a priority queue allows elements with higher priorities to be dequeued before those with lower priorities, regardless of their order of arrival. This behavior is similar to a hospital emergency room, where patients with more critical conditions are treated before those with less urgent issues, regardless of when they arrived. Priority queues can be implemented using various data structures, including heaps (binary heaps are common), arrays, or linked lists. The most efficient implementation is typically a binary heap, which allows for insertion and deletion operations to be performed in O(log n) time complexity. Priority queues are widely used in applications that require scheduling, such as operating systems for task scheduling, Dijkstra's algorithm for finding the shortest path in graphs, and event simulation systems. Understanding priority queues is essential for mastering data structures and algorithms, as they provide an effective way to manage and process elements based on their significance or urgency.