Mongodb is a one of the most popular NO-SQL database management system today. As against the traditional RDBMS, it stores the data in an unnormalized way, in binary JSON format.
Mongodb is an open source document database. The name is derived from Humongous DB. This falls into the category of NO-SQL databases. The data in Mongodb is stored in an un-normalized format, as a collection of documents. A collection in Mongodb is equivalent of a table in RDBMS and a document is equivalent of a record. However, unlike a record, a document need not have the same structure as other documents in the same collection.