What Is Tree in Data Structure With Example?


Heather Bennett

A tree is a widely used data structure in computer science that represents hierarchical relationships between elements. It consists of nodes connected by edges, where each node can have zero or more child nodes. The topmost node in a tree is called the root, and each node in the tree is either a parent or a child node.

Tree Terminology

Before diving into examples, let’s understand some important terms related to trees:

  • Node: A fundamental building block of a tree that contains information and references to its child nodes.
  • Root: The topmost node in a tree that does not have any parent nodes.
  • Parent Node: A node that has one or more child nodes.
  • Child Node: A node directly connected to another node when moving away from the root.
  • Leaf Node: A node that does not have any child nodes.
  • Sibling Nodes: Nodes that share the same parent node.
  • Ancestor Nodes: All the parent nodes on the path from a specific node to the root.
  • Descendant Nodes: All the child nodes on the path from a specific node to its leaf nodes.

Examples of Trees

Example 1: Directory Structure

A directory structure in an operating system is a classic example of a tree. Let’s consider an example:

├── folder1
│   ├── file1.txt
│   └── file2.txt
└── folder2
    ├── subfolder1
    └── subfolder2
        └── file3.txt

This example represents a directory structure with a root directory and several nested folders and files. Each folder is a node, and the relationships between them form a tree structure.

Example 2: Organization Hierarchy

Another example of a tree is an organization hierarchy. Let’s consider the following hierarchy:

├── CTO
│   ├── Senior Developer
│   │   ├── Developer A
│   │   └── Developer B
│   └── Junior Developer
├── CFO
└── COO

In this example, the CEO is the root node, and each employee occupies a node in the tree. The relationships between employees form a hierarchical structure.


Trees are versatile data structures that find applications in various domains like computer science, file systems, organization hierarchies, and more. Understanding the concepts and terminology related to trees is crucial for developing efficient algorithms and solving complex problems.

By incorporating trees into your programming arsenal, you can efficiently represent hierarchical relationships between elements in your applications.

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