In this chapter, we discussed the mathematical definition of a graph and how it is related to graph databases. We then moved on to the specific instance of graph databases we will use throughout this book, Neo4j. We've learned about its building blocks, nodes having labels and properties, and relationships that must have a type and, optionally, some properties as well. We concluded with some important explanations about different types of graphs, weighted, directed, cyclic, or connected, and how this can help in defining the data model best suited to a given use case.
In the next chapter, we are going to look at Cypher, the query language used by Neo4j, and how we can feed the database and retrieve data from it.