State of Connectivity: A Report on Global Internet Access, a new study by Internet.org examines the current state of global internet connectivity and takes a close look at who’s connected, who’s not and why.

The paper uses existing data from the world’s leading sources on connectivity and incorporates our own new findings to examine internet penetration and barriers to further growth.

By early 2015, 3 billion people will be online. This is an incredible milestone, but it also means that only 40% of the world’s population has ever connected to the internet.

The unconnected are disproportionately located in developing countries — 78% of the population in the developed world is online compared to just 32% in emerging economies.

Moreover, adoption of the internet is slowing — The rate of growth declined for the fourth year in a row to just 6.6% in 2014 (down from 14.7% in 2010). At present rates of decelerating growth, it won’t reach 4 billion people until 2019.

In order for the entire world to connect to the internet, we will have to address the three barriers to access: Infrastructure, Affordability and Relevance.

Infrastructure – More than 90% of the world’s population lives within range of a mobile signal. This means that we will need to look at issues like affordability and awareness in order to connect the majority of people.

Affordability – Globally, monthly data plans with a cap of 250MB are affordable to 50% of the population. Reducing this cap to 100MB achieves 80% affordability and 20MB reaches 90% affordability. But in locations like Sub-Saharan Africa where 69% of people live on less than $2 per day, only 53% of the population can afford the internet with a cap of 20MB, an amount that provides just 1-2 hours of web browsing a month.

Relevance – Many people are not online because they are either unaware of the internet or because there is limited relevant content in their primary language. To provide relevant content to 80% of the world would require sufficient content in at least 92 languages.

Read the full report here.

Next Monday March 2, Mark Zuckerberg will discuss efforts to extend connectivity to more people in a session with mobile operators at Mobile World Congress in Barcelona, Spain. The session will take place at 9am Pacific time and can be watched live at mobileworldlive.com.

Update as of February 25, 2015: Because of an editing error, certain numbers regarding affordability in the charts on pages 21, 27 & 28 and in the text on page 27 were incorrect. The report has been updated with the correct numbers.

Update as of March 3, 2015:  The color-coded referents to “developed�� and “developing” countries were mislabeled on the graph Growth of Percent Online on page 10. This error has been fixed.