What Is Node in Data Structure?


Larry Thompson

Node is a fundamental concept in data structures. It plays a crucial role in various data structures like linked lists, trees, graphs, and more. Understanding what a node is and how it functions is essential for developing a strong foundation in data structure concepts.

What Is a Node?

A node can be defined as a basic building block of a data structure. It contains two main components:

  • Data: This refers to the information or value stored within the node.
  • Pointer: This is a reference that points to the next node in the data structure.

The combination of data and pointer makes up a single node.

Nodes in Linked Lists

In linked lists, nodes are used to create a sequence of connected elements. Each node holds both the data and the reference to the next node in the list. The last node typically points to null or an empty space signifying the end of the list.


Node 1       Node 2       Node 3
+------+    +------+    +------+
| Data |    | Data |    | Data |
+------+    +------+    +------+
| Next |--> | Next |--> | Next |--> NULL
+------+    +------+    +------+

The above diagram represents a linked list with three nodes. Each node contains data and points to the next node until reaching null, indicating the end of the list.

Nodes in Trees

In trees, nodes are used to represent hierarchical relationships between elements. Each node can have multiple child nodes but only one parent node (except for the root node). Nodes in trees also contain data and pointers to their child nodes.

        Node A
      /   |   \
  Node B Node C Node D

In the tree above, node A is the root node, while nodes B, C, and D are its child nodes. Each node can have its own set of child nodes, creating a hierarchical structure.

Nodes in Graphs

In graphs, nodes (also referred to as vertices) are used to represent entities. Unlike linked lists and trees, nodes in graphs may not have a specific hierarchical relationship. Nodes in graphs can be connected to multiple other nodes through edges.

   Node A       Node B
     |            |
   Node C       Node D

The graph above shows four nodes (A, B, C, and D) connected through edges. Each node represents an entity or a point of interest.


In summary, a node is a fundamental building block in various data structures. It consists of data and a pointer/reference to other nodes.

Nodes are used to create linked lists, trees, graphs, and more. Understanding the concept of nodes is crucial for developing efficient algorithms and data structures.

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