Problem scenario
You created a PHP web page, but it is not rendering correctly in a web browser. You see the raw PHP code or text. What do you do to get the PHP to display correctly as a web UI (and not raw code and uninterpreted text)?
Solution
Possible solution #1
Install PHP. For assistance with installing it on a Debian/Ubuntu server, see this posting. For assistance with installing it on CentOS/RHEL/Fedora, see this posting.
Possible solution #2
If you are using a Debian derivative of Linux, install libapache2-mod-php. Here is the command that you would run (either with a sudo in front of it or as root):
# apt-get -y install libapache2-mod-php