What is a concurrency token / [Timestamp] attribute?

Short answer: A concurrency token is a property used to detect concurrency conflicts. Example with [Timestamp]: [Timestamp] public byte[] RowVersion { get; set; } EF Core includes this column in the WHERE clause of updates. If the row has changed since it was loaded, EF will throw a DbUpdateConcurrencyException. Entity Framework Core – Relationships

Real-world example (ShopNest)

ShopNest’s order service uses EF Core to save an Order and its line items in one SaveChangesAsync() call inside a transaction.

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.