Before installing first, you need to know what do you
want to use PHP for. There are three main fields you can
use PHP, as described in the What can PHP do? section:
Server-side scripting
Command line scripting
Client-side GUI applications
For the first and most common form, you need three
things: PHP itself, a web server and a web browser. You
probably already have a web browser, and depending on your
operating system setup, you may also have a web server (eg.
Apache on Linux or IIS on Windows). You may also rent
webspace at a company. This way, you don't need to set up
anything on your own, only write your PHP scripts, upload
it to the server you rent, and see the results in your
browser.
While setting up the server and PHP on your own, you
have two choices for the method of connecting PHP to the
server. For many servers PHP has a direct module interface
(also called SAPI). These servers include Apache, Microsoft
Internet Information Server, Netscape and iPlanet servers.
Many other servers have support for ISAPI, the Microsoft
module interface (OmniHTTPd for example). If PHP has no
module support for your web server, you can always use it
as a CGI processor. This means you set up your server to
use the command line executable of PHP (php.exe on Windows) to process all PHP file
requests on the server.
If you are also interested to use PHP for command line
scripting (eg. write scripts autogenerating some images for
you offline, or processing text files depending on some
arguments you pass to them), you always need the command
line executable. For more information, read the section
about writing command
line PHP applications. In this case, you need no server
and no browser.
With PHP you can also write client side GUI
applications using the PHP-GTK extension. This is a
completely different approach than writing web pages, as
you do not output any HTML, but manage windows and objects
within them. For more information about PHP-GTK, please visit the site
dedicated to this extension. PHP-GTK is not included in
the official PHP distribution.
From now on, this section deals with setting up PHP
for web servers on Unix and Windows with server module
interfaces and CGI executables.
Downloading PHP, the source code, and binary
distributions for Windows can be found at
http://www.php.net/. We recommend you to choose a
mirror nearest to you for downloading the
distributions.