Understanding MongoDB Collections
In MongoDB, a collection is a group of documents that are stored together within the database. Collections are analogous to tables in relational databases but are schema-less, meaning each document within a collection can have a different structure.
How to Join Two Collections in Mongodb using Node.js ?
Joining two collections in MongoDB using Node.js can be accomplished using the aggregation framework. The $lookup stage in the aggregation pipeline allows you to perform a left outer join to another collection in the same database.