The HTTP status messages in the 300 series are redirection responses. They indicate that the resource requested has moved or in some way been redirected to a new location.
300 Multiple Choices:
The requested resource corresponds to any one of a number of different options. In most cases the user or the user agent is given a list of choices to choose where to move to.
301 Moved Permanently:
The requested resource has been moved from this URI to a new location. This redirection is permanent. Clients with link editing capabilities should change the link to the new location.
The requested resource resides temporarily in another location, but it can still be found at the requested URI.
303 See Other:
The response to the requested resource can be found at a different URI, but that response should not be cached by the user agent.
304 Not Modified:
If the client has performed a conditional GET request and access is allowed, but the document has not been modified, the server should respond with this status code.
305 Use Proxy:
The requested resource must be accessed by the proxy indicated in the Location: resource.
307 Temporary Redirect:
The resource in question has been moved to a new location, but the user agent should not update the URI to the new location.