How to identify CORS error

Question

I am developing a web application and encountering CORS (Cross-Origin Resource Sharing) errors when making API requests from the frontend. My questions are:

• How can I distinguish between different types of CORS errors (e.g., preflight failures vs. blocked responses)?
• What tools (browser dev tools, cURL, etc.) help debug CORS issues effectively?
• How do I properly configure CORS headers on the server to allow legitimate requests while maintaining security?

A breakdown of common CORS misconfigurations and how to fix them would be helpful.