Originally Posted by Google (Post 102096)

HTML Page
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Using an HTML page as your alternate ad is most useful for creating a 'clickable image' ad. You'll specify the path to an HTML page that contains the information necessary for loading the image, as well as the link code.

There are 2 steps involved in setting an HTML page as your alternate ad: creating the HTML page, and specifying it as your alternate ad.

Creating the HTML page
You'll need to create a simple HTML page that loads your desired image, and contains the hyperlink code. There are a few tricks to successfully creating this code:

Use absolute URLs: we suggest using absolute URLs when you're coding this HTML page. An absolute URL is one that includes the entire, fully-defined path. This ensures that you won't run into any errors when placing the code on various pages of your site.
Use target="_top": this code tells your browser which window to use when loading the destination page of your clickable image. If you don't include this tag in your code (and we'll show you where to include it below) your browser will try to load your destination within the ad format itself.
We've included a sample HTML page below. Note the absolute URLs, as well as the target="_top" tag.



Specifying the HTML page as your alternate ad
Once you've created and saved your HTML page, you'll need to upload it to your server. This page can be hosted anywhere online, as long as it's accessible from the internet.

In the alternate ads text box, simply enter the fully defined path to the saved HTML page. For example:
http://www.example.com/docs/alternatead.html

Click Continue to add your alternate ad selection to the code in your publisher account.