Neo4j Tutorial - Graph Database

Graph Database is a database(DBMS), which used traditional graph methodology to store and display data. Graph database comes under No SQL .
No SQL has many category. They are
1. Document Database
2.Property Database
3.Key value Database
etc
There are many graph databases available in the Industry. Some of them are

Neo4j
HyperGraphDB
OrientDB
Titan

Graph databases use query language to manage data, which is called Cypher Query Language. There is no standard like SQL query  but its easy to learn if you basics of sql.