Reduced Disk I/O: Indexes reduce the need for the database to read large portions?

Short answer: of data from disk. In summary, indexes drastically speed up SELECT queries at the cost of increased overhead during INSERT, UPDATE, and DELETE operations.

Real-world example (ShopNest)

ShopNest adds an index on Orders(CustomerId, CreatedAt) because “my recent orders” is queried constantly.

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.