CORS Error Decoder

The console is throwing a CORS error and the Stack Overflow answers all contradict each other. Paste the error, your frontend origin, the API you are calling and your backend stack. You get a plain explanation of what CORS is, why the browser blocked this specific request, where the fix belongs, and the exact code change for your stack.

I'm getting a CORS error. Here is the error message: {ERROR_MESSAGE}. My frontend is at {FRONTEND_ORIGIN} and I am calling {API_ENDPOINT}. My backend stack is {BACKEND_STACK}.

Explain in plain English what CORS actually is, why the browser is blocking this specific request, and where the fix needs to happen. Then show me the exact code change for my backend stack to resolve it. If there is a quick fix that I should not use in production, tell me what it is and why.