By Ian Sefferman

Here is a question: How can search engine optimization, one of the most important user acquisition channels for Web marketers, be so overlooked in the mobile sector? There is no question why SEO in Web is so popular. It has zero marginal costs per click and it has an extremely high ROI, with engaged users showing intent through their search terms.

If we look at mobile, however, the vast majority of marketers focus on paid ads. 

Forbes reports that mobile ads have accounted for $3 billion in the first half of the 2013, and are growing at 145 percent year over year. Just look at Facebook, which has made billions from app install ads in a move that has almost single-handedly turned it into a company that knows how to monetize in mobile.

This paid ad infatuation is even more interesting when the evidence proves that the majority of users ? 63 percent, to be exact ? find applications through app store search, making it the largest channel for consumer app discovery.

So why are marketers focusing on paid downloads?

Lowdown on optimization
One reason is that it is easier to track exactly where your downloads are coming from and what wording is most effective.

This makes it easy to test, improve and optimize your paid ads. It is much harder to do so for app store search, making app store optimization (ASO) more of an art than a science today. App store optimization ? SEO for the app store ? is also a relatively new and unknown field to marketers.

Lastly, paid ads buy a lot of downloads very quickly, which can help improve an app?s rankings in the app store and lead to a coveted spot in the Top Charts.

For these reasons and more, it makes sense that ASO is being passed over by us app marketers. But is it right for us to do so? Absolutely not.

ASO is the best, but most overlooked, user acquisition for app marketers.

First, just like Web SEO, the marginal costs per install are $0. Each install is effectively free, so good rankings in app store search can drive huge amounts of free downloads.

Second, when users search for something in the app store, they are directly telling you exactly what type of app they want to install ? right now. This intent is what drives high quality users and leads to extremely valuable customers with high lifetime values.

A person searching for a ?note taking? app in the app store is looking for a very specific product, and ensuring your note taking app ranks high is a huge part of making your app successful. ASO does this for you.

We see over and over again that apps which care about ASO generally win in their market.

Pays off
I am in no way saying that paid ads are not important. They are useful and can be extremely effective if used in tandem with ASO.

In fact, paid and organic user acquisition work together in a way that does not happen on the Web: paid ads can help drive Top Charts rankings, which can help drive more organic downloads, which can both help drive higher search rankings, and so on.

Still, many app marketers are missing the second piece in that equation: app store search.

App store SEO may be the most overlooked channel by app marketers, but I have a feeling that will not continue.

As an industry, we will work on building knowledge and tools to help understand our performance in ASO and how to improve.

Ian Sefferman is cofounder/CEO of MobileDevHQ, an app store optimization and app marketing firm in Seattle. Reach him at .