Let's talk in more detail about some of the basic HTTP methods, listed earlier in Table 3-1. Note that not all methods are implemented by every server. To be compliant with HTTP Version 1.1, a server need implement only the GET and HEAD methods for its resources.
Even when servers do implement all of these methods, the methods most likely have restricted uses. For example, servers that support DELETE or PUT (described later in this section) would not want just anyone to be able to delete or store resources. These restrictions generally are set up in the server's configuration, so they vary from site to site and from server to server.
HTTP defines a set of methods that are called safe methods. The GET and HEAD methods are said to be safe, meaning that no action should occur as a result of an HTTP request that uses either the GET or HEAD method.
By no action, we mean that nothing will happen on the server as a result of the HTTP request. For example, consider when you are shopping online at Joe's Hardware and you click on the "submit purchase" button. Clicking on the button submits a POST request (discussed later) with your credit card information, and an action is performed on the server on your behalf. In this case, the action is your credit card being charged for your purchase.
There is no guarantee that a safe method won't cause an action to be performed (in practice, that is up to the web developers). Safe methods are meant to allow HTTP application developers ...