How to filter distinct objects by a property?

Short answer: How to filter distinct objects by a property? var distinctByDept = employees .GroupBy(e => e.Department) .Select(g => g.First()); Explanation: Groups employees by department and selects one employee from each group to get distinct departments.

Real-world example (ShopNest)

ShopNest filters active products with products.Where(p => p.IsActive && p.Stock > 0) before showing the catalog.

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.