Like a regular queue or stack data structure, but where additionally each element has a "priority" associated with it.
An element with high priority is served before an element with low priority.
If two elements have the same priority, they are served according to their order in the queue.
While priority queues are often implemented with heaps, they are conceptually distinct from heaps.
A priority queue is an abstract concept like "a list" or "a map"; just as a list can be implemented with a linked list or an array, a priority queue can be implemented with a heap or a variety of other methods such as an unordered array.