Can PHP detect the calling url ?

[Nxs]

Im writing a script that would need to take different actions according to the domain which it is installed.

Is it possible for PHP to detect the URL its being run from ? or would I need to look at something else.

[Eric]

<a href="http://www.php.net/reserved.variables#reserved.variables.server" target="_blank">http://www.php.net/reserved.variable...riables.server</a>