What is the difference between synchronous and asynchronous programming in Node.js? How does the event loop work in Node.js? What are React hooks, and why are they used? Explain the difference between props and state in React. What is virtual DOM in React.js? How do you create REST APIs using Express.js? What is middleware in Node.js? Explain DFS (Depth First Search) with an example. How do you traverse a binary tree using DFS? What is the difference between BFS and DFS?