Question

How can I detect the site the user came from before accessing mine in PHP?

Answer 1

Try this:

$_SERVER['HTTP_REFERER']

For more information, please see HTTP referrer:

The referrer, or HTTP referrer—also
known by the common misspelling
referer that occurs as an HTTP header
field—identifies, from the point of
view of an internet webpage or
resource, the address of the webpage
(commonly the URL, the more generic
URI or the i18n updated IRI) of the
resource that links to it. By checking
the referrer, the new page can see
where the request came from.