What Is Node in Tree Data Structure?


Scott Campbell

What Is Node in Tree Data Structure?

A node is a fundamental component of a tree data structure. It is an essential building block that stores data and maintains links to its child nodes, if any. Nodes are used to represent elements or entities within a tree, such as files in a file system, web pages on a website, or even individual items in a hierarchical menu.

Structure of a Node

A node typically consists of two main parts:

  1. Data: This is the information or value associated with the node. It can be any type of data, depending on the specific use case.

    For example, if we have a tree representing employees in an organization, the data stored in each node could be the employee’s name, ID number, or any other relevant details.

  2. Pointer(s): These are references that point to other nodes within the tree. The number of pointers can vary depending on the type of tree and its implementation.

The most common types of nodes include:

  • Root Node: This is the topmost node in a tree and serves as the entry point for accessing all other nodes. A tree can have only one root node.
  • Internal Node: These are nodes that have at least one child node.
  • Leaf Node: Also known as terminal nodes or external nodes, these are nodes that do not have any child nodes.

The Role of Nodes in Tree Traversal

In addition to storing data and maintaining links to child nodes, nodes play a crucial role in traversing or navigating through a tree structure. Tree traversal refers to the process of visiting each node in a tree exactly once.

There are several commonly used algorithms for tree traversal:

  • Inorder Traversal: In this traversal, nodes are visited in the order: left child, current node, right child.
  • Preorder Traversal: Here, nodes are visited in the order: current node, left child, right child.
  • Postorder Traversal: This traversal visits nodes in the order: left child, right child, current node.


In summary, a node is a fundamental component of a tree data structure. It stores data and maintains references to its child nodes.

Nodes are essential for representing elements or entities in a hierarchical manner and play a vital role in traversing through the tree. Understanding nodes is crucial for effectively working with tree data structures and performing operations such as insertion, deletion, and searching.

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