This document discusses binary heap trees, which are complete binary trees used to efficiently store and retrieve the maximum or minimum element. There are two types: max heaps, where the parent is always greater than or equal to its children, and min heaps, where the parent is less than or equal to its children. Binary heaps support operations like insertion and deletion of elements in O(log n) time and are often used to implement priority queues and algorithms like Prim's and Dijkstra's.