List of key HTTP status codes and their explanations

HTTP Status Codes and Their Meanings.

1. 200 - Success: The server successfully processed the request.
2. 201 - Created: The request has been fulfilled, resulting in the creation of a new resource.
3. 300 - Level status codes: These status codes are all about redirecting.
4. 301 - Moved Permanently: The page at a certain URL has been permanently moved to a new URL.
5. 302 - Found: The page is at a new URL, but this is a temporary change.
6. 304 - Not Modified: The resource being requested has not changed (used for caching).
7. 400 - Bad Request: The server cannot process the request due to a client error.
8. 401 - Unauthorized: The client must authenticate itself to get the requested response.
9. 402 - Payment Required: Payment is required before the server can process the request.
10. 403 - Forbidden: The client does not have permission to access the content.
11. 404 - Not Found: The server cannot find the requested resource.
12. 500 - Internal Server Error: The server encountered a situation it doesn't know how to handle.
13. 501 - Not Implemented: The server does not recognize or support the request method.
14. 503 - Service Unavailable: The server is not ready to handle the request.
15. 504 - Gateway Timeout: The server, while acting as a gateway or proxy, did not receive a timely response from an upstream server.

The document also provides a summary, highlighting that HTTP status codes range from success (200, 201) to various types of errors (400-series and 500-series).