Here in the tutorial on PHP I read:
If your server supports PHP you don't need to do anything.
Just create some .php files in your web directory, and the server will parse them for you. Because it is free, most web hosts offer PHP support.
However, if your server does not support PHP, you must install PHP.
Firstly, I am not quite sure what it means to "install PHP" here. (How can a programming language be installed?)
Secondly, does this mean that I can go to any free host, even a host that doesn't support PHP, "install PHP" on it and it will start doing all PHP tasks for me?