In this lesson I'm going to give you a concise overview of how web publishing with PHP works. Any kind of web publishing really revolves around the web server. It's the web server which interacts directly with the Internet browser, sending and receiving information back and forth to the client. FileMaker does not develop or distribute web server software, so for custom web publishing to work, you'll be required to provide your own. In these lessons we will be using the Apache web server that comes with Mac OS 10. It doesn't really matter which web server you use, as long as it's compatible with FileMaker Server 9's custom web publishing with PHP. For a list of compatible servers, consult the FileMaker Server 9 documentation. Regular web publishing in general works in the following manner: the Internet browser makes the request for a web page, such as an HTML document. The web server, which is listening for such a request, locates the requested HTML page on its local hard drive. Once the HTML page has been retrieved, the web server passes the contents of the page directly back to the browser. This complete cycle is web publishing in a nutshell. It's commonly referred to as static web publishing because the contents of the HTML is not generated at the time of request. In static web publishing, the HTML is only updated during regular or irregular periods of time. Now let's bring PHP into the loop. PHP is a code engine module, or a CGI, which is loaded into your web server software. You don't manually start or manage the PHP application. Once it's installed, it automatically loads when the web server starts up and gives the web server the ability to process PHP code. To deploy custom web publishing with PHP, you will need to ensure that your web server has the PHP engine installed. If your web server does not have PHP installed, I recommend that you use the PHP installation that comes with FileMaker Server 9. This version of PHP is fairly current and is also supported by FileMaker to work with the new FileMaker API for PHP. Let's look again at the flow of web publishing now that we have PHP processing enabled. As before, the web browser sends a request to the server for a web page. However, this time the web server will need to make a decision about the type of page requested. PHP pages are usually signified by a file name ending with .PHP, while HTML pages are usually signified by a file name ending with .HTML. If the file requested is a traditional HTML file, then the web server sends the contents of the file back to the browser as before. However, if the file requested is a PHP file, then the web server passes the contents of the file to the PHP processor. The processor will then go through the document, executing any and all PHP code. When the PHP processor is done, it will then pass only the results for the output of the processing back to the web server. The web server then returns these results back to the browser. This, in a nutshell, is web publishing with PHP.