It's the new frontier for the internet - connecting billions of people in Africa and Asia who have yet to sample the delights of the digital world. Through an organisation called Internet.org, Facebook has put itself at the forefront of this mission.
Today it unveils a clever plan to get millions of people in Zambia online. It is without doubt a laudable philanthropic mission - but in the long run it could also be hugely important to Facebook's growth.
As Guy Rosen of Internet.org explained to me over a video link from Facebook's Menlo Park headquarters, 85% of those people who aren't connected to the internet are in places with mobile phone coverage. There are two reasons why, despite the widespread use of mobile phones, they have not tried the internet - affordability and awareness. In other words, data use on a mobile phone is far too expensive for most people and they have no idea of what advantages it might offer them.
The plan in Zambia is to address both those issues. The mobile operator Airtel - like a number in Africa - has been offering a simple Facebook experience for free on mobile phones. Now in Zambia it will offer an Internet.org app which will supply Facebook but also a number of other web services. Users will get access to Wikipedia, job sites, weather forecasts, and information about health, all without paying any data charges.
Users will be able to access these web services from simple feature phones by visiting the internet.org website, and they will get a warning if they stray onto sites where data charges apply. Only 15% of the 15 million people in Zambia have used the internet so far - now it is hoped that many more will try it. If the pilot is successful, the same method will be used with other mobile operators in other parts of Africa.
Now Airtel is obviously forgoing some revenue from data to get this scheme off the ground, in the hope that some of those who try out the internet on a mobile will pay for the service in the future. But I was somewhat surprised to learn that Facebook is making no contribution to the cost of the data.
Mobile phones will provide the first experience of the internet for the vast majority of those now trying it for the first time. The words "internet" and "Facebook" are already said to be interchangeable in some places in Africa. Now this initiative is bound to make millions more see Facebook as the gateway to the online world.
Mark Zuckerberg's passionate interest in internet.org's mission certainly seems genuine. But a business with 1.3 billion users that needs to to show investors that those numbers are continuing to rise will now be looking to Africa and Asia to increase its audience. So the philanthropic mission of internet.org and Facebook's long-term business strategy are in perfect alignment.