Chapter 1. Graphs Are Everywhere

Graphs are all around us. Each time we access the Internet, the data packets travel across a network of routers, switches, and cables and deliver what we have requested. While representing key concepts/objects in a problem and defining relationships or interactions between the concepts/objects involved, we generally draw bubbles or boxes to denote the objects, and arrows between those objects to represent the interactions or relationships. We use a similar notation while drawing a map to explain routes to others. The beauty of these notations, such as bubbles and arrows, is their expressiveness, a property that is usually lost when we obfuscate the model into records and tables. Graphs allow us to discover information and ease the modeling pain, which eventually makes our life smoother. To be able to use graphs better, we will need to understand a few basic concepts related to a graph database. In this chapter, we will explore the following:

• Graphs in mathematics
• The property graph model
• Reasons for using a graph database
• Usage of graphs—some obvious and some not-so-obvious graph problems
• Advantages of using Neo4j

We chose Neo4j to explain graph data modeling in this book. However, the modeling concepts discussed here will apply to any graph database.

A few readers might be experienced Neo4j users and if you fall into this category, you might want to skip this chapter. However, if you are new to Neo4j or want a brief refresher, please carry on.