What is the purpose of the $in operator in MongoDB?

Short answer: The $in operator is used to match values in a specified array. It checks if the value of a field is equal to any value in the provided array.

Example code

db.collection.find({ age: { $in: [25, 30, 35] } }); This query finds all documents where the age field is 25, 30, or 35.

Real-world example (ShopNest)

ShopNest’s SQL Server database stores customers, products, and orders. Good indexes and clear foreign keys keep checkout queries fast and safe.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.