mod_php not installed/working by default on debian

php files are not parsed by the server.

mod_php4 does not exist in /etc/apache2/mods-available

libapache2-mod-php4 package is not installed, trying to install it causes apache2-mpm-worker to be uninstalled (I don't know if that's what I need to do)

What other modules that aren't enabled by default on Debian should be enabled?

Closed (fixed)