PHP Web Services, 2nd Edition

Appendix A. A Guide to Common Status Codes

This section outlines some of the most common status codes in use in HTTP APIs, their meaning, and some notes about when they can be used.

Code	Meaning	Notes
100	Continue	For a large request, a client can send just the headers and Expect: 100-continue as an additional header. If the 100 status is received in response, the client can then send the request as normal. Think of it as “go ahead”—in fact, many libraries will handle this for you and make the second request without further prompting.
200	OK	This is good news; everything worked as expected.
201	Created	A new resource was created. This is often accompanied by a Location header or a representation of the new resource in the body of the request.
202	Accepted	This is useful if something is taken to be actioned later, such as being placed on a queue for asynchronous processing.
204	No Content	The request was successful, but there is nothing to return. Perhaps this is the result of a DELETE request.
301	Moved Permanently	The content is at a new location, and this is a permanent change. Links to the old URL must be updated, and this change will often be cached for long periods.
302	Found	This is much like a 200, but the content was not at the location specified. Usually this is seen when an application uses rewrite rules.
304	Not Modified	This is sent in response to a request that included information such as an ETag or Last-Modified, which indicates that the resource ...