Full Stack Development interview questions and answers

The frontend is the user interface that runs in the browser. The backend runs on the server and handles business logic, databases and APIs.

The virtual DOM is a lightweight in-memory representation of the UI. React compares changes and updates only the parts of the real DOM that changed.

A REST API exposes resources over HTTP using standard methods such as GET, POST, PUT and DELETE, typically exchanging data in JSON format.

SQL databases are relational with fixed schemas and use SQL. NoSQL databases like MongoDB store data in flexible formats such as documents and scale horizontally easily.

Middleware functions run during the request–response cycle and can modify requests, responses, handle authentication, logging or errors before passing control to the next function.