Yes.
Yes, it is true that MongoDB uses BSON (Binary JSON) to represent document structure. BSON is a binary-encoded serialization of JSON-like documents and is the primary data representation for documents in MongoDB. It adds some additional data types and encoding to JSON to better support the data types used in MongoDB, such as ObjectId, Date, and binary data. BSON is designed to be lightweight and efficient for both storage and data interchange within MongoDB.