Definition:Component of Graph

Definition
Let $G$ be a graph.

Let $H$ be a subgraph of $G$ such that:


 * $H$ is connected


 * $H$ is not contained in any connected subgraph of $G$ which has more vertices or edges than $H$ has.

Then $H$ is a component of $G$.

Example
This graph has $4$ components:


 * Components.png

Also see

 * Definition:Connected Graph: a graph with only one component.