App.js 90%

It defines the "routes" or URLs of your API—for example, telling the server what to do when someone visits /home or tries to /login .

Because it is the starting point, beginners often make the mistake of putting all their code in this one file. Professionals recommend modularizing your code into smaller components to avoid a "monolithic" App.js that becomes impossible to maintain. 2. The Node.js Server (The "Brain") app.js

Developers often keep "global" state in App.js so it can be passed down to any child component that needs it. It defines the "routes" or URLs of your