# Introduction to graphs

## Introduction to graphs

A graph is a collection of nodes connected by edges. A graph is also frequently called a network, a node may be called a vertex, and an edge may be called a link. Commonly, a graph is denoted by an ordered pair ${\displaystyle G=(V,E)}$, where ${\displaystyle V}$ is the set of nodes and ${\displaystyle E}$ is the set of edges.

Edges are the abstraction of some kind of relation between nodes, e.g. similarity, vicinity, communication, etc. We can distinguish directed and undirected edges.