MERN Must Know

This branch covers the glue between React, Express, Node.js, and MongoDB.

Topics here

• MERN architecture.
• Frontend vs backend responsibility.
• API contract.
• Authentication flow.
• Protected routes.
• Full-stack error handling.
• CORS in MERN.
• Environment variables.
• Deployment overview.

Practice rule

For every full-stack feature, write the complete flow:

UI action -> API request -> server validation -> database operation -> response -> UI update