Inside the science of contextual matching

As an AdSense Product Manager for ads quality, I'm part of a group that
works to make the ads on your site relevant for users. One of the habits
we do this is through background targeting, which matches ads to the
content of your webpages. With contextual targeting, our system parses
and analyzes the content of your page, conducts an auction among the
pertinent ads, then serves the winning ads -- all in the blink of an
eye! Pretty simple, right?
Actually, matching relevant ads to the content of your pages is quite a
scientific challenge connecting semantic analysis and machine learning.
It's a challenge that keeps me and my team busy. Our machines are very
good at the matching process, but there are still a few cases where
their definition of relevance differs from our human meaning of
relevance. In these few cases, the scheme might end up portion ads that
don't seem immediately relevant to users. We understand that greater than before
ad relevance contributes to a positive knowledge for users,
publishers, and advertisers, so we're continuously working on ways to
improve the relevance and quality of ads that come into view on your sites.
I'm excited to let you know that this week, we'll be rolling out a
series of enhancements to AdSense's contextual targeting capabilities,
which will more precisely match relevant ads to webpages. You won't
need to update your AdSense account or ad code, as these changes will
be applied automatically. In many ways these types of improvements are
par for the course at Google - but I wanted to let you know about the
kinds of improvements we've been focusing on. Please keep in brain that
these changes won't have an effect on how other types of ads are matched to your
sites; for instance, you'll continue to see placement-targeted ads when
advertisers bid to come into view specifically on your pages.
This is by no means the end of our labors to perfect the system, but
we believe that with these changes users will start to see even more
relevant ads, advertisers will generate more attractive income by
finding the right users, and publishers should make more money over
time.
As always, we're interested in your criticism on these improvements!
Posted by Woojin Kim - AdSense manufactured goods Manager