Is the anchor part of a URL being sent to a web server?

The answer to this question is similar to the answers for Retrieving anchor link in URL for ASP.NET.

Basically, according to the standard at RFC 1808 - Relative Uniform Resource Locators (see Section 2.4.1), it says:

"Note that the fragment identifier is not considered part of the URL."

As stephbu pointed out, "the anchor tag is never sent as part of the HTTP request by any browser. It is only interpreted locally within the browser".

The hash variables aren't sent to the web server at all.

For instance, a request to http://www.whatismyip.org/#test from Firefox sends the follow HTTP request packet

GET / HTTP/1.1
Host: www.whatismyip.org
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 115
Connection: keep-alive
Cache-Control: max-age=0

You'll notice the # is nowhere to be found. Pages you see using # as a form of navigation are doing so through javascript. This parameter is accessible though the window.location.hash variable

The anchor part (after the #) is not sent to any $_SERVER variables in PHP. I don't know if there is a way of retrieving that piece of info from the URL or not (as far as I know, it's not possible). It's supposed to be used by the browser only to find a location in the page, which is why the page does not reload if you click on an anchor like so: <a href="#hello">hello</a>