What are Relational Databases? Relational databases store their data in columns and rows. Rows are also called tuples or records. Together, the columns and rows make tables which have relationships (keys) to other tables. One table has an unique Primary Key, while the other table has a Foreign Key in a One to Many relationship. What are Graph Databases? Relational databases are the current most common database technology and have been for many years. However, they are not the only horse in the race. GraphDBs are the child of fellow math geeks who found uses for Graph Theory. Graph Theory is the study of the connections of vertices, nodes, or points which are connected by edges, arcs, or lines. Like a GraphDB, each of these objects can have their own properties. For example, lines can have magnitude and nodes can have weight. GraphDBs such as Neo4j, have two main objects: Nodes and Relationships (which connect the nodes).