3. npm Callback Error Troubleshooting
   Understanding the Error:cb(): This refers to a callback function that is expected to be called at some point during the execution of an asynchronous operation
4. Example Codes for Heroku + Node.js Error (Web process failed to bind to $PORT)
   Heroku: A cloud platform that lets you deploy and manage applications.Node. js: A JavaScript runtime environment that allows you to run JavaScript code outside of a web browser
5. Code Examples:
   Git: A version control system that tracks changes in your codebase, allowing collaboration and reverting to previous states