20110630

HTTP Status Codes for Beginners

Informational
·         100 - Continue
A status code of 100 indicates that (usually the first) part of a request has been received without any problems, and that the rest of the request should now be sent.
·         101 - Switching Protocols
HTTP 1.1 is just one type of protocol for transferring data on the web, and a status code of 101 indicates that the server is changing to the protocol it defines in the "Upgrade" header it returns to the client. For example, when requesting a page, a browser might receive a static code of 101, followed by an "Upgrade" header showing that the server is changing to a different version of HTTP.
Successful
·         200 - OK
The 200 status code is by far the most common returned. It means, simply, that the request was received and understood and is being processed.
·         201 - Created
A 201 status code indicates that a request was successful and as a result, a resource has been created (for example a new page).
·         202 - Accepted
The status code 202 indicates that server has received and understood the request, and that it has been accepted for processing, although it may not be processed immediately.
·         203 - Non-Authoritative Information
A 203 status code means that the request was received and understood, and that information sent back about the response is from a third party, rather than the original server. This is virtually identical in meaning to a 200 status code.
·         204 - No Content
The 204 status code means that the request was received and understood, but that there is no need to send any data back.
·         205 - Reset Content
The 205 status code is a request from the server to the client to reset the document from which the original request was sent. For example, if a user fills out a form, and submits it, a status code of 205 means the server is asking the browser to clear the form.
·         206 - Partial Content
A status code of 206 is a response to a request for part of a document. This is used by advanced caching tools, when a user agent requests only a small part of a page, and just that section is returned.
Redirection
·         300 - Multiple Choices
The 300 status code indicates that a resource has moved. The response will also include a list of locations from which the user agent can select the most appropriate.
·         301 - Moved permanently
A status code of 301 tells a client that the resource they asked for has permanently moved to a new location. The response should also include this location. It tells the client to use the new URL the next time it wants to fetch the same resource.
·         302 - Found
A status code of 302 tells a client that the resource they asked for has temporarily moved to a new location. The response should also include this location. It tells the client that it should carry on using the same URL to access this resource.
·         303 - See Other
A 303 status code indicates that the response to the request can be found at the specified URL, and should be retrieved from there. It does not mean that something has moved - it is simply specifying the address at which the response to the request can be found.
·         304 - Not Modified
The 304 status code is sent in response to a request (for a document) that asked for the document only if it was newer than the one the client already had. Normally, when a document is cached, the date it was cached is stored. The next time the document is viewed, the client asks the server if the document has changed. If not, the client just reloads the document from the cache.
·         305 - Use Proxy
A 305 status code tells the client that the requested resource has to be reached through a proxy, which will be specified in the response.
·         307 - Temporary Redirect
307 is the status code that is sent when a document is temporarily available at a different URL, which is also returned. There is very little difference between a 302 status code and a 307 status code. 307 were created as another, less ambiguous, version of the 302 status code.

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