This may be a stupid question, but is it possible to capture what a user typed into a Google search box, so that this can then be used to generate a dynamic page on the landing page on my Web site?
For example, let’s say someone searches Google for “hot dog”, and my site comes up as one of the search result links. If the user clicks the link that directs them to my Web site, is it possible for me to somehow know or capture the “hot dog” text from the Google search box, so that I can call a script that searches my local database for content related to hot dogs, and then display that? It seems totally impossible to me, but I don’t really know. Thanks.
Yes, it is possible. See HTTP header Referer. The Referer header will contain URL of Google search result page.
When user clicks a link on a Google search result page, the browser will make a request to your site with this kind of HTTP header:
Just parse URL from request header, the search term used by user will be in q -parameter. Search term used in above example is “http header referer“.
Same kind of approach usually works also for other search engines, they just have different kind of URL in Referer header.
This answer shows how to implement this in PHP.
Referer header is only available with HTTP 1.1, but that covers just about any somewhat modern browser. Browser may also forge Referer header or the header might be missing altogether, so do not make too serious desicions based on Referer header.