Any relational database has a typical schema design that shows number of tables and the relationship between these tables. While in MongoDB, there is no concept of relationship.
Schema less − MongoDB is a document database in which one collection holds different documents. Number of fields, content and size of the document can differ from one document to another.
Structure of a single object is clear.
No complex joins.
Deep query-ability. MongoDB supports dynamic queries on documents using a document-based query language that's nearly as powerful as SQL.
Ease of scale-out − MongoDB is easy to scale.
Conversion/mapping of application objects to database objects not needed.
Uses internal memory for storing the (windowed) working set, enabling faster access of data.
Document Oriented Storage − Data is stored in the form of JSON style documents.
Index on any attribute
Replication and high availability
Fast in-place updates
Professional support by MongoDB
Content Management and Delivery
Mobile and Social Infrastructure
User Data Management