NEW YORK (TheStreet) -- Facebook (FB) - Get Report is a seasoned company by Silicon Valley standards, so its growth in advertising market share over its relatively short life is easily taken for granted. The little Harvard side-project is not only competing with tech titanGoogle (GOOGL) - Get Report for online advertising dollars, it's gaining ground.

Facebook's secret weapon is mobile advertising, a market that is expected to grow 75% globally to nearly $32 billion this year, according to eMarketer estimates. With an influx of cash flooding online advertising, Facebook is managing to snap up the growth at a far greater pace than Google.

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While Google still receives the majority of global mobile ad revenue at around half the total, its supremacy is slipping. By the end of 2014, eMarketer expects its mobile market share to fall to 46.8% from 52.6% two years earlier. Over the same period of time, Facebook is expected to accelerate its mobile ad revenue share to 21.7% from 5.4%., with its growth primarily at the expense of Google with very little change in share seen from other players such as Twitter (TWTR) - Get Report and Pandora  (P) .

Of course, this isn't to suggest Google is at risk of losing its heft. In the 10 years since its IPO, the Mountain View, Calif.-based company has increased total revenue 21 times to $66.7 billion, while advancing its revenue share of global Internet advertising revenue to 32% from 15%. That's even as its reliance on advertising was reduced to 90% from 98.6% as the company diversified into hardware offerings such as smartphones and wearable tech.

But Facebook is still making an impression, already eclipsing Google in total display advertising in the U.S. eMarketer (which tallies desktop and mobile display ad revenue under the same umbrella) predicts that by the end of this year Facebook will have reached $4.8 billion in digital display sales to Google's $4 billion.

The Menlo Park, Calif.-based social network has succeeded in large part due to its targeting, tracking the likes, dislikes, social interactions of its 1.32 billion-strong user base. It trades in data and advertisers are keen to pay the price for getting the right ad in front of the right person at the right time. Google might know where you go on the Web, but Facebook knows who you are and gives advertisers a demographic added context to utilize.

"Over time, as they amassed more and more information about who is likely to be interested in what, they got better at targeting with both desktop and mobile ads," Jay Hallberg, industry specialist and co-founder and COO of IT social network SpiceWorks, told TheStreet, recounting his early forays into Facebook advertising as unsuccessful. "As an advertiser, they've certainly been improving their products to drive results for us."

"They have had a big focus on quality more than just quantity, so I think that's why they have that growth there," agreed eMarketer analyst Martin Utreras, speaking with TheStreet. "They're not yet monetized to the [highest] levels, so there's lots of potential behind them."

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Facebook's growth also lies in the changing relationship we have with the Internet. Google, once the initial jump-off of any Web experience, is slipping in its place as the only starting point. "People are spending time on Facebook and Instagram. People are spending time in a lot of places that Google isn't," said Hallberg.

Facebook is taking advantage of its migrated audience with new initiatives to ramp up advertising revenue, said Utreras. Video advertising (a segment expected to grow 26% in 2015 to $7.11 billion) is a key focus with its recent acquisition of video ad tech developer LiveRail and as it slowly rolls out multimedia formats across its platforms. Instagram, too, is underutilized in terms of monetization with Facebook preferring the slow introduction of advertising lest it suffocate organic content.

"There still is that rising tide," added Hallberg. "Overall digital advertising is increasing 15-20% year over year so that money is flowing into the market but, whereas in the past that would have flowed heavily to Google, it's now... going to Facebook.

"If Facebook didn't exist, that money might have gone to Google."

--Written by Keris Alison Lahiff in New York.