For display advertising to grow, reach and engagement have to go together or nobody wins.

A note from Editor in Chief & Chief Content Officer Brad Berens: It's worth pointing out that at the time of publication Revenue Science is sponsoring our Behavioral Marketing coverage, but Bill's byline is in no way a part of that sponsorship. You can find a more detailed explanation of our editorial policy here or contact me directly with questions.

Read more coverage of the Google acquisition. We report on news analysis with our Google/DoubleClick Marriage. Tom Hespos weighs in with Google/DoubleClick, You Must Be Kidding; Andreas Roell adds his piece with Googling Up an Empire; Cree Lawson writes The Double-Goo Monster: Are We Jumping at Shadows?  And we hear from Aaron Goldman what we should be looking out for in his, GoogleClick: 10 Things to Keep an Eye On.

Those of us in the industry, let alone the general business press, closely followed the story of Google and Microsoft's amore for DoubleClick that came to fruition late Friday with Google purchasing it for more than $3 billion. And rightfully so. DoubleClick is a great company and very well positioned in our space. But DoubleClick has been a great company for some time now, and hadn't received this type of attention. So why all the interest now, and, perhaps more importantly, what are people missing? The answers are pretty intriguing for those of us in the behavioral targeting world and they ad a timely new context to the "mass v. class" issue for everyone in online advertising.

Why All the Interest?
Remember folks, the compound annual growth rate (CAGR) for our market has been about 90 percent for the last five years, but all of that has come from search. Yes, we have heard that a bunch lately from a variety of people, including myself and Right Media's Mike Walrath. We both talk about that fact because we see display as a huge source of future growth for the industry.

Furthermore, look at the current leader in display advertising, Yahoo! They are currently at about 75 percent reach on the internet. Wow! Those are broadcast TV numbers from the old days! But look at where they are on engagement, there they stand around 15 percent. That's a problem. Yahoo's Ms. Decker and Mr. Semel have been very direct in their discussions with the financial community about their proposed solution to the engagement problem. Coming from me you can guess that a big part of the answer is behavioral targeting. Specifically, using behavioral targeting to syndicate their audience behavior outside of their owned and operated sites, perhaps on Mr. Walrath's exchange.

So display will be big if all the pieces are in place.

Why Now?
DoubleClick does well in display as we all know, with a great installed base of its DART products for publishers and advertisers. Google, on the other hand, has not done so well in display advertising. We all have heard many rumors about the upcoming release of a "free" ad server from Google, built in part to solve their gap in the display market. Given that, put yourself in the shoes of DoubleClick's Dave Rosenblatt for a minute. It's tough to take an ad serving company public in the face of that threat. Ergo, it was a good time to investigate the "strategic option."

Why did that option exist, you say? The answer is simple: Microsoft's continued dismal performance in both search and display advertising. They could have used the purchase of DoubleClick to outflank Google in display advertising, and leverage some publisher angst around Google's excessive power, both to the benefit of their display business, and, their search ambitions. Further to the "reach-engagement conundrum" mentioned above, DoubleClick's publisher relationships would have provided a very high-quality source of traffic for Microsoft to syndicate onto. Now they will allow Google to raise the overall quality of its off-site traffic.

So DoubleClick has motivation and perhaps intent while Microsoft and Google have the means.

What Are People Missing?
For display to grow, publishers need to provide both "mass" and "class" to advertisers. Reach and engagement have to go together, or nobody wins. What good is a spot market for display ad avails when there is no clear means to differentiate who is looking at that avail? Let's call that the "quality paradox" of the ad exchange model.

Behavioral targeting works very well indeed when there is an infinite supply of pre-emptable inventory, what Mike Walrath often calls the "scale paradox" of behavioral targeting. The only big players to figure that out, and, have all the pieces of the pie in place were Yahoo and AOL. Microsoft and Google had that same target in their sights because DoubleClick is an accelerant to that vision. With Google's win, Microsoft will learn is exactly what Yahoo and AOL have already learned: it is missing the answer to the "quality paradox" and that answer is behavioral targeting.

While the investment and business community may be focused on the evolution of ad exchanges, market consolidation and the impact that DoubleClick's lucrative addition to Google will have on the industry, those of us who care to look a little deeper will see that this is the biggest behavioral targeting story in quite a while.

As Forrest Gump might have said, behavioral targeting and ad exchanges go together "like peas and carrots." It's a meal that the online ad industry is going to be feasting on for years to come.

Bill Gossman is the president and CEO of Revenue Science. Read full bio.