As I already said in the article "What is Php", the server elaborates the php codes producing html code, as shown below:

How we can run a php page in our computer if php needs a server?
In the web, it is possible to download local servers, that is to say programs that simulate a server in your computer. One of them is Apache, that is distributed always with new versions.
If your php script require a database, for example Mysql, you must install in your computer Mysql database and if you want Phpmyadmin that make easier your interaction with the database Mysql.
To conclude this article, to run a php script on your computer
you need the following programs:
- a local server (es: Apache)
- a version of Php (files of Php)
- a database (es: Mysql)
There are packages like EasyPhp or Php Triad that contain Apache,a version of Php,Mysql and Phpadmin.
Good Work!