What Is a Node in Computer Science?

Your computer is powered by hundreds of programs that work together to make your user experience a good one.

Whether it’s how the interface runs or the power supply unit, each aspect of a computer plays an integral role in ensuring that the system runs smoothly and securely.   

Every day, we use Google to search for brands we love or play video games on our phones. But have you ever considered how these applications and programs are built? These programs may have different purposes but they all have at least one thing in common: nodes.

In this post, we are going to break down a ‘node’ and its role in computer science and programming.

Nodes and Data

In computer science, a node indicates a basic unit of data structure. These nodes contain data that is linked to other nodes to create complex structures. These structures are important for computers because they organize a program so it can run effectively. Depending on the needs of a program, a variety of structures exist to organize the data.

Different nodes are connected by a pointer. A pointer references a location in a computer or program’s memory. For example, think of a book. An index page is filled with page numbers that ‘point’ back to the corresponding page.

Types of Structures

In the world of computer science, nodes, and data, you will come across the term data structure, which is the backbone of every piece of software. Data structures help these programs store information and run effectively.

Data structures serve four distinct functions for programs: inputting, processing, maintaining, and retrieving.

  • Inputting: the way information is received
  • Processing: the way information is handled within the structure
  • Maintaining: the way information is organized
  • Retrieving: the way information is accessed and used

While there are eight common data structures, the two most common data structures that use nodes are called linked lists and tree structures.

Linked Lists

Linked lists are linear structures. Think of boxes in a straight line with arrows in between each box. Each box is a node containing information and a reference (pointer) to the next node. The arrows link the nodes together. This structure begins with the head, which points to the first node in the sequence.

Linked lists are commonly used because they are not fixed. You can add and delete nodes from it. If you’re unsure about the number of elements or nodes your application will need, linked lists are your best bet.

Let’s break down the three most common types of linked lists:

  • Singly linked list: a node that points to the next node in the sequence. This is unidirectional.
  • Double linked list: a pointer is added that directs back to the previous node in the sequence. This is bidirectional.
  • Circular linked list: the last element is linked to the first element forming a circular loop.

One thing to consider is that linked lists use up memory and don’t allow direct access to the individual nodes in the middle of the sequence.

Tree Structures

On the other hand, a tree structure is a non-linear structure because it doesn’t have a fixed beginning or end. You will find that data organized in a hierarchy. We use this structure to place and locate files in a database. It is a more efficient way to store and find information.

Picture a family tree with many generations. The top is two points (grandparents) that divide into four as they have children. As the family grows, so does the tree.

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Each point on this tree is called a node, which is connected to other nodes by edges. At the very top of the tree structure is the root node where the structure starts. If more nodes are added, the root node is considered a parent node and the connected node a child. The last nodes on the tree structure are called leaves. Leaf nodes have no children and end the structure.

You’ll find this structure used in Java and many other popular programming languages.

Other Node Definitions

When researching nodes, you might see the word being used in terms of computer networks. This particular node indicates a device within a network that can send and receive information. Your computer has a unique IP network address allowing it to function as a node on a network.

If you have two computers and a printer at home, your total node count is three.