A graph database uses graph theory to store, map and query relationships. It is essentially a collection of edges and nodes, with each node representing an entity such as a person or an organization and each edge represents a connection or relationship between two nodes. A node is defined by a unique identifier and has several edges attached to it, whether incoming or outgoing, and it has a set of properties that are expressed as key-value pairs. An edge is also defined by a unique identifier, and it has a start and an end node, as well as a set of properties. A graph database is useful for the analysis of relationships and interconnections between data; hence, it is seeing wide use in data mining of social media data, for data with dynamic schemas, such as in supply chain management, as well as in sales, where it is used to determine the interconnections between a customer’s online actions.