Jamie Leach of Google, announcing the new search results page design last year:
The name of the website and its icon appear at the top of the results card to help anchor each result, so you can more easily scan the page of results and decide what to explore next. Site owners can learn more about how to choose their prefered icon for organic listings here.
When you search for a product or service and we have a useful ad to show, you’ll see a bolded ad label at the top of the card alongside the web address so you can quickly identify where the information is coming from.
Danny Sullivan, tweeting as Google’s “public liaison of search”:
Last year, our search results on mobile gained a new look. That’s now rolling out to desktop results this week, presenting site domain names and brand icons prominently, along with a bolded “Ad” label for ads.
All you get, as far as identifying where a search result comes from, is a tiny 16-by-16-point favicon and small grey text with the URL. If it’s an ad, the favicon is replaced with a little “Ad” label, but there are no other advertising identifiers. Just a few years ago, Google used to indicate ads much more prominently. If the ads are truly as “useful” as Google claims, surely it doesn’t need to trick users into clicking on them instead of regular results.
Update: Google says that they’re going to experiment with different ad and search result appearances.