• Download the latest zipped distribution, not the Windows installer, of PHP from the "Windows Binaries" section of http://php.net/downloads.php.
  Unzip it somewhere on your hard drive.
  You can pick any drive, and any folder, but the recommendation is to put all the PHP stuff in a folder just off of the root drive (avoid whitespace), like C:\PHP, and this guide will follow that recommendation.
• Download the PECL Win32 binaries zip file (should be just below the link to the PHP zip file - DON'T download from the "Non-thread-safe" links) and extract the contents of that archive into C:\PHP\ext. It contains more extensions.
  Move php5servlet.dll and php5activescript.dll from C:\PHP\ext into C:\PHP.

PHP extensions are libraries that extend the functionality of PHP. For example, the file php_gd2.dll provides dynamic image creation and manipulation functions that go beyond what PHP itself does. For information on extensions, visit http://ca3.php.net/manual/en/install.windows.extensions.php and http://pecl.php.net.

The typical, basic PHP installation doesn't require you to do anything with extensions: if you're unsure about extensions you can set extension_dir then continue to step 2.5. Once you get PHP working, you can revisit extensions.

• Point PHP to the correct folder:
  Set extension_dir in php.ini to "C:\PHP\ext"

• Massage the list of extensions so that most of them will load w/out throwing errors.
  The following is a list of the extensions that come with PHP combined with the PECL extensions. I have commented out the ones that either did not work well on my system or that require external software, like the extensions for different databases. I've provided comments about some of them; for more information, refer to the link above. If you want as many extensions available w/out having to use dl() as possible, start with this list and refine it to match your system. Remember, though, that the more extensions you have uncommented in php.ini, the more resources PHP will need to run. I'm not running my server with all of these extensions uncommented, this list just reflects what I found to work.

CONFIG FILE HERE

Final notes on using extensions:

• I left uncommented all the ones that I got to work on my system with no additional software.
• If you have not downloaded and extracted the "Collection of PECL modules for PHP 5.2.3" archive, not all of the files in the list will exist on your system, so many of the uncommented ones will not work.
• Most of the ones that won't load rely on other software being present, like oracle, informix and sybase.
• Actually using php_openssl.dll requires you to follow the instructions in C:\PHP\extras\openssl\README-SSL.txt.
• See the BIG FAT NOTE in section 4.2
• The MySQL connector has to be mysqli for MySQL 4.1.5 or later (extension=php_mysqli.dll). If you copied in the list of extensions above, that line will be in there. If you didn't, well, then it won't.

I could continue for a few more pages commenting on extensions. If you have some particular question, a little google-grease goes a long way. If you're here because of some google grease and don't see the answer to your question, shoot me an e-mail. The worst thing that could happen is that I'll ignore you, and you won't be any worse off than you are now.

(b) is the preferred method (ok, it's my preferred method, but since I'm writing this guide, it's the preferred method ) since not only does it keep the installation in one place, making upgrading or uninstalling easier, but it also allows you to more easily run PHP from the command line.

• right-click on My Computer, choose Properties
• flip to the Advanced tab
• click the Environment Variables button
• Double-click the Path variable in the list of System variables.
• Add "C:\PHP;" (sans quotes) to the beginning. See step 5.9 for an explanation of why it should go at the beginning of the PAH.
• The new PATH will be available to any new command prompt, but not to existing ones; bounce the server if you want to be sure that it will take effect.

This is so that PHP can find its configuration file (php.ini). To make it easy on you, modify the following text so that "C:\\PHP" is the folder in which you've unzipped PHP, then copy the text and paste into a new text file (anywhere; the Desktop is a good place to create it). Rename the file to inifilepath.reg, then double-click on it, click "Yes" to the confirmation dialog, and the value will be in place. You can then delete inifilepath.reg.
Make sure all backslashes are escaped in the .reg file (ie. \\ instead of just \)

Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SOFTWARE\PHP] "IniFilePath"="C:\\PHP"

NOTE: PHP also uses other settings to find its configuration file; one of the most notable being the PHPRC environment variable. I prefer using the Registry because by varying the key, you can configure different versions of PHP to run side-by-side on the same machine. See http://us2.php.net/configuration for more information.

3.

For these steps, open IIS Manager
(Start -> Control Panel -> Administrative Tools -> Internet Information Services (IIS) Manager).

When you open IIS Manager, it should connect to the local computer automatically.

• Expand the local computer in the left pane
• Click on "Web Service Extensions" in the left pane
• In the right pane, click the blue underlined text, "Add a new Web service extension..."
• Enter "PHP ISAPI Extension" as the "Extension name"
• Click the "Add..." button and browse to the php5isapi.dll file in your PHP install folder
• Check the "Set extension status to Allowed" checkbox and click "OK"

There are two ways to setup PHP for the web: ISAPI and CGI. ISAPI is typically more efficient and secure. If you want to add the CGI extension, in addition to or instead of the ISAPI, repeat the above, but enter "PHP CGI Extension" as the "Extension name", and enter the full path to php-cgi.exe (it will be in your PHP install folder along with php5isapi.dll).
Note that I have seen the CGI module misbehave several different ways and recommend that you stick with the ISAPI module.

The following two steps are suggested to apply to the "Web Sites" root folder in IIS Manager, but they can be applied to individual sites, instead. When applying changes to "Web Sites", note that a dialog might come up asking if you want to apply changes to a list of specific websites, too. The listed sites will be ones that have overridden any default values, so be careful about applying changes to them. Especially be careful of applying changes to the Microsoft SharePoint Administration site (thus speaks painful experience).

• Expand the local computer in the left pane
• Right-click on "Web Sites" in the left pane, then click "Properties" in the menu that pops up
• Flip to the "Home Directory" tab
• Click "Configuration"
• Flip to the "Mappings" tab
• Click "Add..."
• Enter the full path to php5isapi.dll in the "Executable" textbox (Browse... to find it more easily if you need to)
• Enter ".php" in the "Extension" textbox
• Select radial button "Limit to", enter "GET,POST,HEAD"
• Click "OK" all the way out

Replace php5isapi.dll with php-cgi.exe if you chose the CGI extension in the previous step.
Again noting that I don't recommend using the CGI module...

Right-click on "Web Sites", goto Properties -> Home Directory.
Change the "Execute permissions" dropdown to "Scripts only".

Right-click the local computer in the left pane of IIS Manager, click on All Tasks -> Restart IIS... -> OK
- OR -
reboot now.

4.

Expand the "Web Sites" folder in the left pane of IIS Manager to see a list of existing websites. Right-click on a website -> Properties -> Home Directory -> Local Path will show you where the website root folder is.
Contents of test.php:

<?php // testing sessions // check to see if files are being created // in the session.save_path folder session_start(); ?> <html> <head> <title>PHP Test</title> </head> <body> <p> The browser you're using is <?php echo $_SERVER['HTTP_USER_AGENT']; ?> </p> <p> <!-- test the browscap setup --> Your browser's capabilities are: <br/> <pre> <?php print_r(get_browser(null, true)); ?> </pre> </p> <?php phpinfo(); ?> </body> </html>

If you did not setup session or browscap support as outlines in steps 2.2 and 2.3, then remove the sections that test them.

*** BIG FAT NOTE: If you uncommented extensions, be sure to test this while logged in to the server's console. If some of the extensions throw errors when loading, an error dialog will pop up on the server console telling which one didn't work. You have to be able to click "OK" to the dialog for the page to finish loading. The dialog will pop up ONLY on the server's console; not even Terminal Services will show it. Take note of the extension that didn't work, click "OK", and then comment out the extension in php.ini until you can figure out how to get it to work.
IMPORTANT TIP: if you can't get physical access to the server, you can connect to the console via RDC. Click on Start, then Run... and enter the following in the text box: "mstsc -console" (sans quotes) to start RDC in "console mode". Once you login, you will be able to see the console message dialogs. If you're using the OS X RDC client, hold down the Apple (Command) key when you click Connect. A dialog will pop up asking if you want to connect to the console. Click Yes and you're on your way. ***

Addendum to the BFN: Kristopher Hom was kind enough to point out to me that the extension errors will be logged in System Event Log (Right-click on My Computer, choose Manage..., System Tools, Event Viewer, System). The error he saw was, "Application popup: Warning : PHP Startup: Unable to load dynamic library 'C:\PHP5\ext\php_mysql.dll' - The specified module could not be found." See step 5.3 for more information about mysql errors.

Another addendum to the BFN: An alternate way to test extension loading is to run PHP from the command line (Start -> Run -> type "cmd" and hit Enter). If you followed my suggestion in step 2.5, just type "php" and see if any errors appear. Comment out the offending extension and repeat.

After loading test.php, you should see some ugly-looking information about your browser spewed across the top of the page (if you setup browscap support), followed by some nicely-formatted information about your PHP installation. Be sure to scroll all the way down to the bottom to see that there were no errors. I noticed with my installation that if I used CGI, the last several modules wouldn't load and a bunch of error messages would print at the bottom of the test page.
Also go check your session folder (if you setup session support) for a 0-byte file. That's the file to hold session data for the session you started by using the command session_start().

5.

If you setup IIS to use the ISAPI extension, then try this: right click on WebSites > Properties > ISAPI Filters > Add
filtername = PHP
executable = php5isapi.dll

It seems that since we've added an ISAPI extension, we would need to add an ISAPI Filter, but I never had to. I added one to see what happened, and couldn't tell if it made any difference in performance, or even if it was being used.

Make sure that the value of the browscap variable in php.ini is the full path to the browscap.ini file, not a relative path.

Did you uncomment any extensions in step 2.4? If an extension errors while loading, PHP throws up a dialog box to the console of the server displaying the name of the extension and the error. In order for PHP to continue processing (e.g., in order for the page to continue loading), you have to click the "OK" button on the dialog box.
I know, I know, pretty stoopid, but that's the way it is.
Go login to your server's console (not just Terminal Services, the dialog doesn't show up there) and click "OK" to the 50 million dialogs that have popped up there (one for each time you frustratedly restarted IIS and tried to load the page again).
Then go re-comment out the troublesome extension(s) and try it again, this time keeping an eye on the server console.
Make sure you have the extensions in the order specified in 2.4; that order has been tested to load all the uncommented extensions w/out complaining.
Make sure you have downloaded and installed the "Collection of PECL modules for PHP 5.0.3" as described in step 1.1
As mentioned in step 4.2, the extension errors will be logged in System Event Log (Right-click on My Computer, choose Manage..., System Tools, Event Viewer, System).
If you see any errors involving php_mysql.dll, be sure you have followed step 2.5 and either copied the non-PHP dlls from your PHP install folder to %systemroot%\windows32, or have added your PHP install folder to the PATH and either bounced the server or bounced IIS. The mysql errors typically come from PHP's inability to find the supporting mysql library (libmysql.dll) when it loads php_mysql.dll. Making sure libmysql.dll is in the PATH somewhere ensures that PHP can find it.

Even if you followed my recommendation in step 2.5 and added the PHP install path to the server's PATH environment, try putting the dll files - php5ts.dll especially - in the system32 folder. Several people have written in to say that's what they had to do.

You may have spaces in you PHP install folder path. Try changing the PHP install folder to be simply "C:\PHP" and see if that will get it working.

I've seen this happen when trying to use the CGI module (php-cgi.exe). Don't use the CGI module. Use the ISAPI module.
I have seen several problems with the CGI module, and do not recommend that you use it.

If your website is set up to run in a special Application Pool, our the user of your default pool is a non-standard one, you may need to give a different user permission to the PHP files and folders.