1) What is the difference between unit of work and repository pattern? 2) How does dependency injection work? 3) Where and why the Identity Framework and JWT tokens are used. 4) How to configure development server, production server and test server configuration files in the same project so that the project can run on any server later. 5) What is Docker and why is it needed and how does it work? 6) Why is background service needed and how does it work? 7) What's the difference between a string and a string builder? 8) How does index work in database?