MongoDB is a NoSQL document database — it stores data in JSON like documents. Schema is flexible — every document can have different fields. It is good for applications where data structure changes frequently. I used MongoDB in all my projects — Zentra, DocuMind, FurnishHub — because data was dynamic and changing during development.
BSON stands for Binary JSON. MongoDB stores data in BSON format internally — it is a binary representation of JSON that supports more data types like Date and supports faster parsing.