On the other hand, collection contains sets of documents and functions as equivalent of relational database tables. MongoDB supports dynamic schema design just like NOSQL databases, which allows the documents in a collection having different fields and structures.
The mongo database was released to open source in the year 2009 and is available under the terms of the free software foundation GNU AGPL Version 3.0 commercial license. Features of this database are: Indexing: Fields in this database document can be indexed with primary and secondary indices. Replication: MongoDB Contributes high availability with replica sets. A replica set includes two or more copies of data.