Neo4j is one of the most popular open-source graph database.

A graph database shows the relationships between data in a graphical manner.

Neo4j stores the data in the nodes, and nodes are directed by nature.

Neo4j is a graph database that follows the graph theory.

In Neo4j, the data are represented as nodes and edges, and each node or edge can have one or many attributes.

Neo4j supports a SQL-like query language called Neo4j CQL(Cypher Query language)

Neo4j also provides a beautiful Web UI that users can use to create and retrieve the data.

Neo4j also supports REST APIs which can be accessed through various programming languages.