The most common instructions to installing php5 and apache is the following: sudo apt-get install php5 sudo apt-get install libapache2-mod-php5 sudo /etc/init.d/apache2 restart
However, you can just install apache and libapach2 mod and run php5. So why do you need the php5 package if the libapach mod package runs it just fine??
The php5 package is a metapackage whose job is solely to ensure that one of a number of different ways of running PHP for websites is installed. In actual use it's completely unnecessary; it's a convenience for people who just want PHP5. Type sudo apt-get install php5 on a system without PHP5 at all, and it'll prompt you with the options available.
