What is the Aggregation framework in MongoDB?

Short answer: How do you use it? The Aggregation Framework in MongoDB is used to perform complex data processing tasks such as grouping, filtering, sorting, and reshaping documents. It uses a pipeline of stages to process documents:

Example code

db.collection.aggregate([ { $match: { status: "active" } }, // Filter documents { $group: { _id: "$age", count: { $sum: 1 } } }, // Group by age and count occurrences { $sort: { count: -1 } } // Sort by count in descending order ]);

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.