# Graph Data Structure Types - Directed, Cyclic, Weighted, Connected

Different types of graph exist. Directed acyclic graph, Directed & Undirected graph, Weighted & Unweighted graph, Cyclic graph, Strongly connected graph, Polytree, Forest.

## Types of Graph - Based on Direction & Weight

### Directed Graph (or) Digraph

Directed Graph is a graph in which each edge has a direction to its successor.

### Undirected Graph

Undirected Graph is a graph in which there is no direction on the edges. The flow between two vertices can go in either direction.

### Weighted Graph

If the graph has a some cost or weight on the edge, then we say that graph is said to be a weighted graph. Weight can be applied in both Directed and Undirected graph.

### Unweighted Graph

If there is no cost or weight on the edge, then we say that graph is an Unweighted Graph. For example, Figure 2 is the Unweighted Undirected graph

## Types of Graph - Based on How Connected the Graph is

### Strongly Connected Graph

If there is a path from each vertex to every other vertex in the directed graph, then only we say that directed graph is said to be Strongly connected graph.

### Weakly Connected Graph

If there are at least two vertices that are not connected, then we say that directed graph is said to be weakly connected graph.

### Disjoint Graph

The graph is a disjoint, if it is not connected.

### Complete Graph

If there is an edge between every pair of vertices, then we say that graph is said to be complete graph.

## Types of Graph - Based on Cycles

### Acyclic Graph

A graph is acyclic if it has no cycles.

### Directed Acyclic Graph

A directed acyclic graph is directed graph without any directed cycles. Referred by its short name **DAG**

### PolyTree

PolyTree is a directed graph without any undirected cycles

### Forest

Forest is a undirected graph without any cycles