Did you ever wonder if, and how, the ads that you sprinkle on your pages affect your site's ranking? How do search engines differentiate between the content of those paid ads and your own content or banners? How do SEO and ads manage to live side by side? Like cats and dogs: they need to learn to live together.
We did a bit of digging into what Google engineers and SEO luminaries had to say about the subject and came up with some interesting findings. In this article, we'll look at
We will look at potential markup strategies needed to isolate ads from the rest of your website content -- thus avoiding any direct impact on your SEO.
Let's get this definition out of the way: what are digital ads? Ads are sponsored gateways. In online advertising, an ad is a banner, a media block or a link embedded on a web page to promote an external resource, brand or product. The ad is typically shared by the host in exchange for either money or another form of credit.
According to that definition, propping up your own site or its content does not count as an advertisement: it is an internal link, regardless of how elaborate the link's appearance is, or even where it appears. If you were to place a link to your own homepage on a flashy animated banner and put that banner on your website, it would not count as an ad, anymore than a standard hyperlink would.
Adverts come in countless shapes and forms. However, there's only two broad categories of advertisement on the web: display and native.
The most obvious kind is the display ad. Not surprisingly -- given its name -- the display ad is the type of ad you see almost everywhere. They are often bold and obnoxious, but this is by design.
On the other hand, native ads: product placements, referral links and "sponsored links" that are displayed inline with the content flow. More often than not, native ads blend in both in style and in form with the content. In other words, native ads are designed to be visually coherent with the content in which they appear.
Where display ads stand out visually while remaining on the margins, native ads are cloaked but insidious, as they make their way inside the main content so that visitors cannot easily identify or avoid them. They are insidious.
You could think of Native vs. Display ads as you would Aliens vs. Predators. Alien ads come from another world: they look out of place, they are utterly annoying and they stalk the users' visual space from the margins (they hide in the docks.) Predator ads are cloaked: they pretend to be part of the environment but still prey on the users whenever they have a chance to strike.
Most -- but not all -- paid display advertisement is rendered in iframes.
An iframe is a section of a page that displays the HTML pulled from a different URL. You can think of iframes as holes in your page: areas where external HTML content is presented through a window.
For indexing purposes, web crawlers will ignore everything that they find in an iframe. For example, Google's spider ignores its own Adwords ads, and it will not follow the links or execute click actions anywhere within those ads.
While display ads are typically presented in iframes, some are rendered as images. This use of inline elements can confuse the search engine as it tries to interpret the page's intention. In such cases, the author needs to ensure that the advertisements not isolated in an iframe is properly tagged. This will avoid unnecessary penalties. The best way to structure the markup is to place the image in a <picture /> element within an <aside />. Additionally, all links within a paid advertisement should be tagged with NOFOLLOW (as in: rel="nofollow".)
When modern search engines crawl the text content of a web page, they look primarily for two things: relevance and coherence. In the scope of a given keyword, the more relevant and focused the content, the better the rank. But content needs more than just relevant: it also needs to be coherent.
Let's look at a theoretical example: Imagine a web page that is all about vintage cars and that displays ads. One of those ads is for fashionable handbags. From a marketing perspective, there's no coherence issue here. However, search engines do not expect the main content to suddenly veer off-subject, praise some novelty item and link to an external commercial site which is about novelty handbags. Such would appear suspicious and incoherent to the search engine, just as it would to any human visitor. While search engines don't have a clue what cars or fashion are, they do know how words are related. Through formal analysis of the content's linguistic structures, search engines are able to evaluate the coherence of a web page's copy based on these known syntactic and semantic relationships.
In a typical web page layout, display ads do not blend in with the content. The same way products advertised on television have no relationship with the current programming, display ads are relegated to the edges of the page for a reason. There's a good reason for this: display ads are inherently disruptive, as they are designed to be so. It's a convenient thing that humans are particularly adept at discriminating their visual environment. Human readers quickly learn to jump over, or ignore anything that's not in their focus of interest -- e.g., the copy of an article or the frames of a video. Human readers tend to proceed as if that extra content displayed by the ad did not exist. The more ads they encounter, the better they become at ignoring them.
As far are reading a web page is concerned, robot crawlers can do more or less the same as their human counterparts. The main difference is they are designed to be thorough: this is why they need formal clues in order to discriminate the content. In other words, web authors need to indicate to the spiders which parts of the content is an ad, and which part is intended to be relevant. This is where the markup comes in.
In the eyes of a search engine crawler, there are few if any difference between a display ad and a spammy link: both point to external resources that has little if anything in common with the content. How is a crawling bot supposed to know whether what it is looking at 1) an ad, or 2) content authored by an erratic and incoherent human being?
The less ads and distractions -- such as outbound links, general purpose widgets, etc. -- on a page, the cleaner it is. Clean pages are easy to read and can act as references. This is why a clean web page will always rank slightly higher than a dirty one, even when they have the exact same content.
You can easily guess that the opposite is also true: dirty pages are difficult to read and therefore rank lower than their cleaner sisters. To be clear: by dirty, I mean a page polluted with adverts which distract from the original intent by making it difficult to navigate, let alone understand, the main content.
The problems with advertising banners