On PHPit.net today, there's a new tutorial targeted at anyone out there looking to roll your own ad system for your site.

Most of us who run websites will most likely want to add advertising on our websites some time in the future. The easiest way to do this is to simply take the advertising code (be it HTML or JavaScript), and paste it directly into the code of our HTML. But what if we eventually get multiple advertisers for the same spot?

In that case you must use some sort of advertising management script. The best one around, phpAdsNew, is completely free and can be downloaded at http://www.phpadsnew.com, but this might be slightly overkill for most websites.

In this article, the first part of a new three part series, I will show you how to build your own advertising system. In this first part I will take you through the basics of dynamic JavaScript, and how to serve multiple advertisements in the same spot. Let's get started.

He starts with the Javascript side of things, showing how to use an included JS file to create dyanmic content (much like the Google Ads). From there, it's all a matter of PHP on the backend that pulls out the content you need and pushes it back out to the patiently waiting Javacript...