200 OK - Standard response for successful HTTP requests.
201 Created - The request has been fulfilled, resulting in the creation of a new resource.
204 No Content - The server successfully processed the request and is not returning any content.
3xx Redirection
304 Not Modified - Indicates that the resource has not been modified since the version specified by the request headers If-Modified-Since or If-None-Match.
4xx Client Error
400 Bad Request - The server cannot or will not process the request due to an apparent client error (e.g., malformed request syntax, too large size, invalid request message framing, or deceptive request routing).
401 Unauthorized - Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided. The response must include a WWW-Authenticate header field containing a challenge applicable to the requested resource.
403 Forbidden - The request was a valid request, but the server is refusing to respond to it. The user might be logged in but does not have the necessary permissions for the resource.
404 Not Found - The requested resource could not be found but may be available in the future. Subsequent requests by the client are permissible.
409 Conflict - Indicates that the request could not be processed because of conflict in the request, such as an edit conflict between multiple simultaneous updates.
5xx Server Error
500 Internal Server Error - A generic error message, given when an unexpected condition was encountered and no more specific message is suitable.