Trees are hierarchical data structures consisting of nodes connected by edges, with a single root node and sub-nodes. They are used to represent relationships and organize data hierarchically.

Trees are a fundamental data structure in computer science that represent hierarchical relationships between data elements. A tree consists of nodes connected by edges, starting with a single root node at the top. Each node can have zero or more child nodes, creating a parent-child relationship. This structure is particularly useful for organizing data hierarchically, making it easy to model relationships such as organizational structures, file systems, and family trees. One of the key characteristics of trees is that there is only one path between any two nodes, which allows for efficient traversal and search operations. There are several types of trees, including binary trees, where each node has at most two children; binary search trees (BST), which maintain a sorted order; and more advanced structures like AVL trees and red-black trees that self-balance to ensure optimal performance. Another common type of tree is the trie, which is used for efficient string searching and retrieval. Tree traversal methods include depth-first search (DFS) and breadth-first search (BFS), both of which can be implemented using recursion or iteration. Trees are widely used in various applications, including database indexing, expression parsing, and implementing data structures like heaps. Understanding trees and their properties is essential for mastering data structures and algorithms, as they form the basis for many complex systems in computer science.