“WordPress plugins abound for Google AdSense and other
third-party text ad brokers, but what happens when someone wants to
buy ad space directly from you, on a specific category page in your
blog? You can easily add static HTML text ads to your category
search result pages by creating category-specific page
templates.“Because most WordPress themes have a single template for
archives, aptly named archive.php, it’s not immediately apparent
how to place a text ad on a specific category results page…”