It’s not new for search engines to advertise on other search engines. We wrote about Live.com doing that on Google earlier this year, and that was just the latest in a long line of examples over the years. But we’ve never heard of a search engine advertising for those seeking another search engine on a third search engine until now.

The screenshot above explains it all. It’s a search for yahoo.com on Google, bringing up an ad from Ask.com. Ask — going after Yahoo users who are searching for Yahoo at Google.

It’s a pretty popular query, actually. I wrote recently about how Yahoo is one of the most popular search terms on Google, even above some of the terms that were originally mistakenly reported by Google as the most popular last year. More recently, Yahoo was even found to have more queries that perennial top search "sex" on Google.

It is odd that these ads don’t show in the US. Someone tipped us to the ad after spotting it in Germany, and I can see it in the UK. But in the US, it’s not showing.

This is a good time to remind people how to see ads targeted to various countries. To do this, simply add:

&gl=COUNTRYCODE

The country code is a two digit combination for a particular country. The UK code works like this:

http://www.google.com/search?q=yahoo.com&gl=gb

The two letter country codes can be found here, and more information about country targeting can also be found here from Google.

Related Topics: Ask: Promotions | Google: AdWords | Search Ads: General

About The Author: Danny Sullivan is editor-in-chief of Search Engine Land. He’s a widely cited authority on search engines and search marketing issues who has covered the space since 1996. Danny also oversees Search Engine Land’s SMX: Search Marketing Expo conference series. He maintains a personal blog called Daggle (and maintains his disclosures page there). He can be found on Facebook, Google + and microblogs on Twitter as @dannysullivan. See more articles by Danny Sullivan