You may have noticed that I’ve got Google Adsense adverts on my blog and photo gallery. Not that either of them is popular enough to generate significant income (in fact, it’s generally so insignificant that it’s practically invisible), but just on the off-chance that I suddenly become famous (or infamous) and loads of people start Googling me then I want to get something out of it! But it does give me some interesting insight into what goes on at the Adsense backend.

For those who aren’t familiar with it, the way Adsense works is that Google spiders your web page and indexes that so that it knows what words you’ve got on it. At the other end of the system, advertisers create ads and then bid on certain keywords that they want to trigger it.  So, for example, travel agents might bid on words or phrases like “hotels” and “summer holiday”, ISPs might bid on terms like “broadband”, “VOIP” and “BTInternet sucks”, and ambulance-chasing lawyers might bid on “industrial accident”, “mesothelioma” and “asbestos cancer”. If your page matches a keyword that’s being bid on, then that advert gets shown on your site.

Anyway, the thing about the photo gallery is that it’s primarily images – which don’t affect Adense as it’s entirely text based. And most of the text on the gallery is common to all pages – things like the header and sidebar – so the only difference between individual pages is the title and caption of the image and gallery.  So if I get different adverts on different galleries, then it has to be the album and image titles themselves that are the relevent keywords. And, in many cases, the captions are still the filename (something like “DSCF01234”), which isn’t particularly interesting.

In most cases, the results are what you’d expect. For example, the photos of Barcelona get adverts for travel agents. The photos of the U2 gigs get ticket agencies. The photos of the cats get adverts for pet food suppliers. Rather amusingly, the food photos get adverts for, inter alia, diet programmes! But the one that intrigues me is that photos of an event run by a former employer carry adverts for a different organisation, working in the same field but in many respects a direct rival. And this is one where the image captions are just filenames, and the category name carries other adverts in different albums. Plus, thse adverts don’t appear anywhere else on the site. So the only thing that can be generating those particular adverts on those pages is the name of my former employer, as that’s the only factor which is present only there and nowhere else. Which means that the rival organisation is actually bidding on that name when placing adverts. They want you to see adverts for them when looking at websites talking about my former employer.

That’s perfectly legitimate, but it still seems a tad sneaky. It’s the equivalent of Barclays bidding on “Lloyds” as a keyword, or Microsoft bidding on “Linux”. And it makes me wonder how much of this is going on in the Adsense world – how many adverts are deliberately placed alongside copy relating to a rival. Hmmm.