In data structures, the term “adjacent node” refers to a node that is connected directly to another node in a graph or a tree. Understanding the concept of adjacent nodes is crucial for various algorithms and operations performed on data structures.

## Adjacent Nodes in Graphs

In graph theory, a graph is a collection of nodes or vertices connected by edges. Each edge represents a relationship or connection between two nodes. In this context, adjacent nodes are those that share an edge.

Let’s consider an example. Suppose we have a graph with three nodes: A, B, and C. If there is an edge connecting node A and B, and another edge connecting B and C, then A and B are adjacent nodes, as well as B and C.

To represent adjacent nodes in HTML code:

```
<p>
<ul>
<li><b>Node A</b> - Adjacent to <b>Node B</b></li>
<li><b>Node B</b> - Adjacent to <b>Node A</b>, <b>Node C</b></li>
<li><b>Node C</b> - Adjacent to <b>Node B</b></li>
</ul>
</p>
```

## Adjacent Nodes in Trees

In trees, which are a type of graph with no cycles, adjacent nodes have some additional characteristics. In a binary tree, each node has at most two children: a left child and a right child. The left and right children of a node are considered adjacent nodes.

For example, in a binary tree with nodes labeled A, B, C, D, E, and F, if node A has a left child B and a right child C, then B and C are adjacent nodes.

To represent adjacent nodes in HTML code:

```
<p>
<ul>
<li><b>Node A</b> - Left Child: <b>Node B</b>, Right Child: <b>Node C</b></li>
<li><b>Node B</b> - Parent: <b>Node A</b></li>
<li><b>Node C</b> - Parent: <b>Node A</b></li>
</ul>
</p>
```

## Conclusion

Understanding the concept of adjacent nodes is vital for various operations performed on graphs and trees. Whether you are traversing a graph or implementing algorithms like breadth-first search or depth-first search, knowing the adjacent nodes of each node is essential for efficient problem-solving.

In this article, we learned that adjacent nodes in graphs are those connected by edges, while in trees, adjacent nodes are the left and right children of each node. By utilizing the appropriate HTML styling elements such as __underlined text__,

- unordered lists

,

,

## subheaders

, and **bold text**, we can create visually engaging and organized content.