It may sound like ancient history at this point, but do you remember when Facebook (NASDAQ:FB) went public in 2012? Much like a rabid dog, the market and the media latched on and would not let go of this little tidbit found in Facebook's initial S-1 Registration Statement: "Growth in use of Facebook through our mobile products, where we do not currently display ads, as a substitute for use on personal computers may negatively affect our revenue and financial results."

It's true that at the time, Facebook had no mobile monetization strategy in place, and this concerned investors considering the unstoppable rise of mobile devices. This was primarily why Facebook shares promptly plunged following the IPO, sparking all sorts of controversy. But the reality is that Facebook hadn't even started trying in earnest yet to build a mobile advertising business at that point.

Myth dispelled
In January 2013, Mark Zuckerberg made it clear: "I want to dispel this myth that Facebook can't make money on mobile. It may have seemed like that a year ago, because we weren't really trying yet." And just look at what happened once Facebook started trying.

Source: SEC filings.

Over the course of just 3 years, mobile advertising has risen from just 3% of advertising revenue to an overwhelming 76% of advertising revenue. That's incredible progress transforming what was once a prominent risk factor into the driving force of the business.

If you think that's impressive, it gets better.

Show me the money
While mobile's percentage of advertising revenue has skyrocketed, so too has Facebook's top line revenue. If we translate it all into dollar figures, we see a robust mobile advertising business that brought in $2.9 billion in sales last quarter. That's up from just $30 million three years ago.

Source: SEC filings and author's calculations.

Needless to say, Facebook has come a long way.

Monetization matters
But Facebook's user base has also expanded meaningfully over the years. Not only does the company continue to add new users all around the world, the texture within the user base has also evolved. Naturally, mobile usage is on the rise. Facebook now has 1.3 billion mobile MAUs, and 655 mobile-only MAUs that exclusively access the service on a mobile device.

Beyond looking at total mobile advertising revenue in dollar terms, Facebook has gotten extremely good at monetization. Mobile average revenue per user has skyrocketed and now sits at $2.27.

Source: SEC filings and author's calculations.

Put another way, as recently as Q4 2013, Facebook's worldwide ARPU was just $2.14, and now the company is able to monetize mobile usage even better than that.

Three years is an awfully short period of time to turn such an initially negative storyline into such a positive one. Make no mistake, Facebook is a mobile company.