MongoDB is a NoSQL Database. It is an open-source document-oriented database and written in c++. it is used for a high volume of data storage. It is not a relational database. It has important features like indexing, regular expression, sharding data, etc.
Advantages:-
Schemaless
Scalability
Performance
High Availability
etc.
Note:- Datastore in the MongoDB as a key-value format.
Example:-
employees collection
{ name:"John", age:35, department:"Department A" }
Mongo DB works based on collection and Document
Collection:- Collection is a group of MongoDB documents. It is the equivalent of an RDBMS table but it has not enforced to the same structure of the document so it is possible documents have a different structures in the collection.
Document:- it is based on key-value pairs and document the same as a row in RDBMS. Documents have a dynamic schema. Dynamic schema means that documents in the same collection do not need to have the same set of fields or structures.
Example:- employees collection
One Document has this structure
{ name:"John", age:35, department:"Department A" }
The second Document has a different structure
{ name:"John", age:35, skill:["NodeJS","Angular","MongoDB","MySQL"], department:"Department A", }
compare RDBMS and Mongo DB structure
MongoDB
Table
Row
Column