1XX (Temporary response)
100 (continued) The requesting person shall continue to make the request.
101 (switching protocol) The requestor has asked the server to switch protocols, the server has confirmed and is ready to switch
2XX (Success)
200 (success) The server has successfully processed the request.
201 (created) The request was successful and the server created a new resource.
202 (accepted) The server has accepted the request but has not yet processed it.
The 203 (non-authoritative information) server has successfully processed the request, but the information returned may be from another source.
204 (no content) The server successfully processed the request, but did not return any content.
The 205 (reset content) server successfully processed the request, but did not return any content. Unlike the 204 response, this response requires the requestor to reset the document view (for example, to clear the form contents to enter new content).
The 206 (partial content) server successfully processed a partial GET request.
3XX (redirected)
300 (multiple choices) for requests, the server can perform a variety of operations.
301 (permanently moved) The requested page has been permanently moved to a new location.
302 (temporarily moved) the server is currently responding to requests from different locations, but the requestor should continue to use the original location for future requests.
303 (View other locations) The server returns this code when the requester should use a separate GET request for the different locations to retrieve the response. For all requests except HEAD, the server automatically goes to a different location.
304 (not modified) The requested page has not been modified since the last request. When the server returns this response, the Web page content is not returned
305 (using proxies) the requestor can only use the proxy to access the requested Web page. If the server returns this response, it also indicates that the requestor should use the proxy.
307 (temporarily redirected) the server is currently responding to a request from a Web page in a different location, but the requestor should continue to use the original location for future requests. This code, similar to the 301 code that responds to the GET and HEAD requests, automatically transfers the requestor to a different location, but you should not use this code to tell Googlebot that a page or site has moved because Googlebot continues to crawl the original location and index it.
4XX (Error request)
The 400 (Error request) server does not understand the syntax of the request.
401 (not authorized) Request authentication required.
403 (Forbidden) The server rejected the request.
404 (Not Found) The server could not find the requested Web page.
405 (Disabled method) disables the method specified in the request.
406 (not acceptable) could not respond to the requested Web page using the requested content attribute.
407 (requires proxy authorization) This status code is similar to 401 (unauthorized), but specifies that the requestor should authorize the use of the proxy. If the server returns this response, it also indicates which proxy the requestor should use.
409 (conflict) The server encountered a conflict while completing the request.
5XX (server error)
500 (Server internal error) The server encountered an error and could not complete the request.
501 (not yet implemented) The server does not have the capability to complete the request. For example, this code may be returned when the server does not recognize the request method.
502 (Error Gateway) The server acts as a gateway or proxy and receives an invalid response from the upstream server.
503 (Service Unavailable) The server is not currently available (due to overloading or downtime maintenance). Typically, this is only a temporary state.
504 (Gateway Timeout) The server acts as a gateway or proxy, but does not receive requests from the upstream server in a timely manner.
505 (HTTP version not supported) The HTTP protocol version used in the request is not supported by the server.
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HTTP various status code detailed
