> For the complete documentation index, see [llms.txt](https://soveet-nayak.gitbook.io/algorithms/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://soveet-nayak.gitbook.io/algorithms/graph/introduction.md).

# Introduction

A graph data structure is a collection of nodes that have data and are connected to other nodes.

More precisely, a graph is a data structure (V, E) that consists of

* A collection of vertices V
* A collection of edges E, represented as ordered pairs of vertices (u,v)\\

### Graph Terminology <a href="#term" id="term"></a>

* **Adjacency**: A vertex is said to be adjacent to another vertex if there is an edge connecting them. Vertices 2 and 3 are not adjacent because there is no edge between them.
* **Path**: A sequence of edges that allows you to go from vertex A to vertex B is called a path. 0-1, 1-2 and 0-2 are paths from vertex 0 to vertex 2.
* **Directed Graph**: A graph in which an edge (u,v) doesn't necessarily mean that there is an edge (v, u) as well. The edges in such a graph are represented by arrows to show the direction of the edge.