✅ Programming Concepts – Interview Questions 💻⚡

🧠 Core Programming Concepts
1. What is the difference between compiled and interpreted languages?
2. What is OOP? Explain its 4 pillars.
3. Difference between Abstraction vs Encapsulation?
4. What is Polymorphism? Give a real example.
5. What is the difference between Stack and Heap memory?
6. What is Recursion? When should you avoid it?
7. What is the difference between Pass by Value and Pass by Reference?
8. What are mutable vs immutable objects?
9. What is a deadlock?
10. What is multithreading?

🧩 Data Structures & Algorithms Concepts
11. What is Time Complexity?
12. Difference between Array and Linked List?
13. When would you use a HashMap?
14. Explain Binary Search and its complexity.
15. What is a Stack Overflow error?
16. What is a Queue vs Priority Queue?
17. What is Dynamic Programming?
18. What is Greedy Algorithm?
19. Explain Big-O notation.
20. What is Space Complexity?

🗄 Database & SQL Concepts
21. What is Normalization?
22. Difference between Primary Key and Foreign Key?
23. What is Indexing and why is it used?
24. Difference between INNER JOIN and LEFT JOIN?
25. What is a Transaction? Explain ACID properties.

🌐 System & Backend Concepts
26. What is an API?
27. Difference between REST and SOAP?
28. What is Authentication vs Authorization?
29. What is Caching?
30. What is Load Balancing?

⚡ Advanced Conceptual Questions
31. What is Dependency Injection?
32. What is Design Pattern? Name some common ones.
33. What is Microservices Architecture?
34. What is Event-Driven Architecture?
35. What is Race Condition?
36. What is Memory Leak?
37. Explain Garbage Collection.
38. What is Lazy Loading?
39. What is Idempotency in APIs?
40. What is SOLID principle?

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