Mobile ad network AdMob claims to have served more than 100 billion mobile ads over the last three years since the company's launch.

AdMob says its milestone means that mobile is mainstream, especially with smartphone shipments worldwide projected to grow 13 percent this year to 164 million units. AdMob claims it is partnering with advertisers, publishers and application developers to make the mobile advertising experience more dynamic and relevant for consumers with smartphones.

"We are extremely proud of the work we've done to help bring the mobile industry forward, an industry that has historically been a complicated place to do business," said Wendy Dikes, director of product marketing at AdMob, San Mateo, CA. "We're proud to be the first to hit 100 billion mobile ads.

"AdMob was also the first to create unique rich-media ad units for mobile, including many highly engaging media-rich options for the iPhone," she said.

"Our goal is to continue to provide the tools, data and business models that are helping fuel the explosive growth of mobile advertising worldwide today."

To help people conceptualize 100 billion, AdMob provided comparisons for perspective:

One hundred billion is more than 14 times the entire world population in 2008, 107 times the distance in miles from the Earth to the Sun and approximately one-half to one-fourth - depending on which scientist you believe - of the number of stars in the Milky Way galaxy.

AdMob shared credit with the advertisers, agencies, application developers and mobile Web publishers with which it has worked.

The company claims it has been growing alongside the explosion of smartphone devices that have redefined the mobile ecosystem.

In June 2009 AdMob served ads on more than 16 million unique iPhone and iPod touch devices worldwide, according to the June 2009 AdMob Mobile Metrics Report.

In 2008, the estimated number of mobile subscriptions outpaced wired Web users.

Mobile subscriptions exceeded 4 billion versus 1.5 billion wired Web users, according to the International Telecommunications Union, a United Nations agency.

In addition, the evolution of the mobile Web has positively affected mobile advertising.

Not that long ago, mobile used to mean simple WAP sites or trying to view a traditional Web site with a subpar transcoded experience. Mobile Web sites have come a long way since then and now provide a rich user experience optimized specifically for mobile.

The mobile applications craze spurred by the iPhone has also upped the ante for mobile advertising and marketing.

AdMob claims that by creating an engaging user experience, click-through rates for advertisers in its network have soared to high levels while new business models have emerged for developers to monetize their applications.

Indeed, as smartphones become more mainstream, having a strong presence in the mobile landscape has become essential for both mainstream brands and emerging developers alike.

"We're very excited to be hitting a milestone like this, and one of the reasons we've been able to grow so fast is that we've pushed for transparency," said Johanna Werther, product marketing manager at AdMob. "We've been transparent with our data all along with our monthly metrics report that shares our traffic and trends in the industry, and we've shared the adoption of the iPhone broadly and openly from the beginning.

"There's a relationship between the transparency we're striving for in the number of unique users we can reach and the methodology we use for measuring that reach," she said. "We feel fortunate to have a lot of great publisher and advertiser partners that have enabled our growth.

"Now iPhone developers represent a significant and growing segment of our clientele."

In a recent blog posting, AdMob addressed the recent story that appeared in Mobile Marketer about Nielsen's study measuring mobile ad networks' reach.

"At AdMob we've been transparent with our methodology, which we think will move the mobile advertising industry forward," Ms. Werther said. "With validated input, Nielsen is a useful, valuable tool.

"We'd like to encourage transparency to make the buying process easier for advertisers and increase their confidence to benefit the growth of the industry," she said. "Reach is just one thing we offer advertisers in addition to performance, reporting and targeting tools.

"There's a whole other story beyond the reach numbers."