Hierarchies are everywhere in computing. Trees provide the discrete mathematical model and the practical data structure that capture these hierarchies precisely. In this chapter, you will learn core tree concepts and study important special cases such as rooted trees, binary trees, and binary search trees (BSTs). These structures underpin common IT operations by organizing data so that meaningful relationships can be exploited algorithmically.

We begin by building intuition for trees and their properties, including equivalent characterizations. From there, we focus on BST operations (search, insertion, deletion) and show how in‑order traversal yields a natural sort. You will analyze how height drives performance. The chapter then turns to decision trees, a complementary use of tree structure for modelling conditional logic in computing contexts, such as access control or troubleshooting, where each internal node encodes a test, and each leaf represents an outcome.