This document discusses leftist heaps, which are a type of priority queue implemented as a variant of a binary heap. Leftist heaps maintain the property that the right descendant of each node has a lower rank, or distance to the nearest leaf node, than the left descendant. This property helps keep the tree balanced during operations like insertion and merging of heaps that have a time complexity of O(log n). Deletion of the minimum element involves disconnecting and merging the left and right subtrees.