Friday, 26 January 2007

How Google Targets AdSense Ads

There is a lot of speculation about how Google actually targets AdSense ads. Does it read the keywords meta tag? Should you put keywords in b(old) tags? What about em, strong, or i(talic) tags? Does font-size matter? What about the title tag? And so on.

To make matters worse, I regularly read messages from supposed AdSense experts stating with apparent authority that most of the above really do make a difference, particularly the meta keywords and b tags. So, do these things really make a difference?

Well, the answer to that question was recently supplied by a Google employee and I have kindly been given permission to share that information with you, courtesy of the direct recipient, Jon of Cobnut Web Services.

However, before we take a closer look, we need to examine what we already know from official sources about how Google targets AdSense ads.

What Google Says About Ad Targeting

In AdSense's help pages you will find the following in answer to the question, "How does Google target ads to my website?"

We go beyond simple keyword matching to understand the context and content of web pages. Based on a sophisticated algorithm that includes such factors as keyword analysis, word frequency, font size, and the overall link structure of the web, we know what a page is about, and can precisely match Google ads to each page.
In addition, according to AdSense help, the only method of emphasizing some text over others, and having other text ignored, is by the use of Section Targeting.

Thus, we can conclude from official sources that the factors affecting ad targeting include:
  1. Keyword analysis
  2. Word frequency
  3. Font size
  4. Link structure (overall, web-wide)
  5. Section targeting
However, many of those terms are pretty vague. Do "keyword analysis" and "word frequency" include the keywords meta tag, for example?

One point that is of great interest though is that font size is listed as a factor. I can only assume that this is true whether the font size is declared using font tags or CSS's font-size. Thus, it appears that words in a larger font may be given more emphasis than those in a smaller font. It is also my opinion that this applies mostly to headings and sub-headings that incorporate a larger font, not simply using a large font size for keywords that appear in the middle of sentences (if you see what I mean!).

What Has Been Shared With Me About Ad Targeting

Much of the information I received simply repeats the information above but it also contains a few hidden gems:
Our technology takes into account factors such as linguistics, keyword analysis, word frequency, font size, and the overall link structure of the web. AdSense only targets ads based on overall site content, not keywords within the meta tag or categories . . .
[i]f you'd like to display ads related to specific topics on your website, we recommend including more text-based content about these topics on your site to assist our crawlers in gathering information about your pages and determining relevant ads to display. Complete sentences and paragraphs are helpful to our crawlers in determining the content of a page. (Emphasis not in original.)
So lets, take a closer look at those gems.

Google Does Not Target Ads Based on the Keywords Meta Tag

AdSense only targets ads based on overall site content, not keywords within the meta tag

So, it is the overall site content that counts and not meta tag keywords. This is a very important point because it implies that you should be able to get ads that are relevant to your site even on pages that have low textual content provided there is sufficient text on the site as a whole.

Google Needs Text-Based Content

Now, this piece of information isn't exactly a surprise or new, but it's good to have it re-emphasized by Google that AdSense is contextual advertising with an emphasis on the text! If you don't have text, you won't get targeted ads.

Google Needs "Complete Sentences and Paragraphs"

Thus, if you want well-targeted ads on your site, you don't just need text, you need text that is comprised of complete sentences and paragraphs. That doesn't mean that Google cannot ascertain context from "telegram-style" bullet points or any other text but it does mean that the more keywords you have in complete sentences and paragraphs, the more accurately targeted your ads will be.


So, if you want highly targeted ads on your site, make sure your follow the following guidelines:
  1. Put keywords in larger font-sizes (probably headings/sub-headings, etc.)
  2. Try to ensure that pages linking to your site incorporate your keywords inside the hyperlinks
  3. Use keywords inside internal hyperlinks (i.e. hyperlinks between pages of your own site)
  4. Employ section targeting
  5. Ensure there is sufficient "keyword-rich" text across your site as a whole
  6. Make sure that your keywords are contained in complete sentences and paragraphs
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