I looked at my credit card bill online and was surprised to see competitors advertised on the charge from a different store. For instance, a Safeway charge would have an ad for Kroger, and similar ads for restaurants and a few retail stores. Has this been going on long; this is the first time I have noticed it.
I would need to know more about the context of what you’re referring to, but my guess is that the ads are delivered by analyzing key words on the screen that you’re looking at. GMail does this, so that if you’re e-mailing your friend about gardening tips, you’ll see ads for fertilizer (or whatever).
It’s the new way of things. Not advertising itself, but putting ads on every damn electronically produced bit of anything is. For a bonus rant Safeway gives you coupons for stuff you didn’t buy, ever, but is sort of kind of similar.