PHP

Request methods

There are six request methods, but only three are used in practice:

GET

Retrieves a resource. A query can be used to add extra information to the GET request and, as we discussed in our introduction to URLs, these are appended to the URL itself. A database search is a good example of an application of the GET request: the resource is likely to be a web script, and the query component of the URL is the search conditions.

POST

Sends data to a server. Rather than appending data to the URL, the data is sent in the body of the HTTP request.

HEAD

Returns only the header fields in a response, not the resource itself. This can be used for lightweight retrieval, so that the modification date of a resource can be checked before the full resource is retrieved with GET.

DELETE

Allows a resource identified by the URL to be deleted from a server. This is the counterpart to the PUT method and allows an author to remove a resource from the specified URL. Usually not implemented.

PUT

Similar to the POST method, this method is designed to put a resource onto a server that can be later retrieved with the URL in the PUT request. Some HTML editors and web servers support the PUT methods allowing authors to put resources onto a web site at the specified URL. Usually not implemented.

TRACE

Produces diagnostic information.

The HTTP standard divides these methods into those that are safe and those that aren't. The safe methods-GET and HEAD-don't have any persistent side effects on the server. The unsafe methods-POST, PUT, and DELETE-by their nature are designed to have persistent effects on the server. The standard allows for clients to warn users that a request may be unsafe, and a browser should not resend a request with the POST method without user confirmation.

The HTTP standard further classifies methods as idempotent when a request can be repeated many times and have the same effect as if the method was called once. The GET, HEAD, PUT, and DELETE methods are classified as idempotent; the POST method isn't.

by BrainBellupdated
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