The request has been completed and the rest of the process can continue.
101
Switching Protocols
When requesting a page, a browser might receive a status code of 101, followed by an "Upgrade" header showing that the server is changing to a different version of HTTP.
2xx Success The action was successfully received, understood, and accepted.
The requested address refers to more than one file. Depending on how the server is configured, you get an error or a choice of which page you want.
301
Moved Permanently
If the server is set up properly it will automatically redirect the reader to the new location of the file.
302
Moved Temporarily
Page has been moved temporarily, and the new URL is available. You should be sent there by the server.
303
See Other
This is a "see other" SRC. Data is somewhere else and the GET method is used to retrieve it.
304
Not Modified
If the request header includes an 'if modified since' parameter, this code will be returned if the file has not changed since that date. Search engine robots may generate a lot of these.
305
Use Proxy
The recipient is expected to repeat the request via the proxy.
4xx Client Error The client failed to provide an valid request.