When you need to perform operations that require access to many object types

Short answer: in an object structure. The visitor pattern is particularly useful when operations are performed on different types of objects, and each type requires specific behavior. Drawbacks of the Visitor Pattern:

Real-world example (ShopNest)

Use a GoF pattern in ShopNest only when it removes duplication or makes a change safer—explain the problem it solves in the interview.

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.