As exciting as the past 10 years have been for Facebook (NASDAQ:FB), the coming decade will be all about user engagement for the company. With its growing base of more than 1.2 billion monthly active users, Facebook has reached a critical mass and made the transformation from a novel website into a human behavior.

Facebook is a commonly accepted interface, communication, and marketing tool in today's global society, and its established user base still has the potential to grow as the Internet becomes more available to more users. Think about this: still 65% of the world's population doesn't or can't use the Internet. So Facebook's growth story playing has plenty of acts ahead of it, giving it a great chance to beat the market over the coming decade.

1. Market Opportunity

(See More Stats at Social Ad Spend to Reach $11 Billion by 2017)

Facebook makes its money from advertising, and its market opportunity is huge, particularly in mobile. Worldwide media ad spending is slated to reach $540 billion in 2014, and while digital advertising will make up almost quarter of that total, or about $130 billion, Facebook really has its eye on mobile, which is poised for takeoff. Mobile ad spending is expected to reach $18 billion in 2014 and $42 billion by 2017. For context, Facebook's 2013 revenue clocked in at just under $8 billion, and with fully more than half of Facebook's ad revenue now coming from mobile, it's easy to see why the company is so focused the mobile opportunity today.

2. Leadership

At just 29, Mark Zuckerberg has what looks like a long run ahead of him as the leader of one of the world's most relevant companies. We have seen him move from the overarching perception of a bratty kid to a capable founder and CEO with a tremendous runway of opportunity in front of him to grow Facebook into one of the most successful companies in the history of the world.

For a better understanding, let's turn to Zuckerberg himself and some key quotes that illustrate his development: (Click to see more, plus our take)

Zuckerberg quotes

3. Engagement
As Facebook turns 10, its next decade will be focused on user engagement, as the company works to keep its platform as vibrant, useful, and entertaining as it possibly can. Facebook's strategy for increasing engagement is comprehensive, becoming more things to more people. And for all of the hyperbole about whether Facebook makes money and that teens are defecting at an alarming rate, it sure seems like the company is doing something right.

Data from Facebook.

The growth in daily active and monthly active users is phenomenal, and Facebook is growing its share of the pie all around the world. (See more stats in Facebook's fourth-quarter earnings slides (PDF).)

Make no mistake, a big theme in the coming years in social media will be consolidation — as the big dogs add services to keep users and boost engagement. Facebook tried to acquire Twitter and Snapchat to no avail, but two successful acquisitions were Instagram and SportStream. Facebook just reported that Instagram doubled its user base from a year ago, to an estimated 180 million, as Instagram Video and Instagram Direct offer new ways to communicate. In a more data-driven acquisition, Facebook acquired SportsStream in late 2013 in an effort to do more with the real-time sports talk within its worldwide universe. SportStream analyzes social media mentions related to sports and sporting events and provides information to news outlets and the teams themselves.

The Hacker Way
Zuckerberg's philosophy on how he approaches the work Facebook is doing is called "The Hacker Way," and it's an approach to building that involves continuous improvement: "Hackers believe that something can always be better, and that nothing is ever complete." This means is that Facebook's (ergo Zuckerberg's) work is never done. Users and investors will find the company constantly trying new things and then trying to top it. Every few months the company hosts a "hackathon" where new ideas come to life. Some live. Some die. But all this ultimately leads to a constant focus on new products for customers and users in order to make Facebook a more engaging place. 

Graph Search
Graph Search is Facebook's effort to offer more value to its users based on the data its users are already offering up via pictures, places visited, and businesses or products liked. If you think Graph Search sounds like a massive undertaking, well, you're right. The company is in the early stages of pulling together the nuts and bolts, but it may be the best example of the Hacker Way at work, with multiple iterations and releases as Facebook incorporates Graph Search into its ecosystem.
Today, only one-third of the world's population has access to the Internet, which means there is a phenomenal opportunity for companies like Facebook to lead the way toward connecting the rest of the world. Zuckerberg announced as a partnership uniting some of the world's largest companies in an effort "dedicated to making Internet access available to the two-thirds of the world not yet connected."

The Foolish Bottom Line
I'll be the first to admit that I was skeptical of Facebook as an investment for some time. I'll also be the first to admit that I was wrong. Facebook has the opportunity to be one of the most successful business in history, thanks to a phenomenal market opportunity, a driven founder with so much time in his corner it's scary, and a user base that has taken Facebook from novel website to a common form of communication around the world in just a decade. Advertisers go where the eyeballs are, and there can be no doubt that Facebook is a place where advertisers are realizing plenty of exposure. I think we are onto something of epic proportions here.

Jason Moser owns shares of Twitter. David Gardner owns shares of Facebook. Sarah Goddard owns shares of Facebook. Tom Gardner owns shares of Facebook. The Motley Fool owns shares of Facebook. Photos by Brian Solis (CC). The Motley Fool recommends Apple, Facebook, and Twitter. The Motley Fool owns shares of Apple and Facebook. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.