# What Is A Directed Acyclic Graph?

Understanding the basics of a DAG

## Directed Acyclic Graph

A Directed Acyclic Graph (DAG) is a type of graph in computer science and mathematics that cannot form a loop or cycle. As implied, a DAG is:

Directed: Information flows in one direction.
Acyclic: It cannot form a closed loop circle.
Graph: In computer science, a graph describes a network of relationship links (edges) between nodes.

To better understand the concept, the following examples will help. Where people are nodes and friendship links are edges, this forms your social graph. In your social graph, friendship is bidirectional and forms an undirected and cyclical graph.

A family tree, in contrast, is an example of a graph that is both directed and acyclic.
It is one directional and does not (shouldn’t) loop making it a directed acyclic graph.

The most recognized dynamic DAG (as opposed to linear DAG) in the distributed ledger space is the Tangle. It was released publicly by the IOTA Foundation in 2015.
As a distributed ledger protocol, a dynamic DAG has inherent and significant properties:

– It does not require miners or mining.
– It does not require fees.
– It does not require blocks or a chain.
– Scalability and security improves with heavy network load.

Dynamic DAGs are more representative of a web and store data across distributed nodes.

#### Fluid Architecture

A DAG allows for increased dynamic data flow, which isn't dependent on a singular preceding input, as in a linear structure.

#### Diverse Solutions

A DAG structure is inherently flexible enough to be applied to a broad range of scenarios.

#### Increased Efficiency

The application of a DAG in the DLT space introduces efficiency and long term network sustainability.

#### Shared Interests

A DAG in the DLT space alleviates the need to compete for settlement rewards and promotes mutual benefit to all network users.

### Introduction to Directed Acyclic Graphs

This video illustrates what a Directed Acyclic Graph is and is not as well as how nodes in a DAG can be ordered linearly, for clarity, in a topological sort.

Now you know the fundamentals of a DAG. Understand why IOTA is our DLT of choice: