how do you detect if your website visitor came from a google search result?

Question

when a user searches from google and lands on our site from the results he/she was shown in the results page, is there a way for my site to detect that he came from google?<

Answer 1

Yes, use the HTTP_ REFERER var in the $_SERVER array:

$_SERVER['HTTP_REFERER'];

This shoudl then include something like http://www.google.com/?q=etc

Note however that the REFERER is not always set because clients can disable their browser to send it in the request.