One in three people—2.48 billion—worldwide used a social network in 2017, eMarketer estimates. Rising social network use in emerging markets in Asia-Pacific, Latin America and the Middle East and Africa drove an 8.7% gain over 2016.

Social media use in digitally advanced markets in North America and Western Europe is widespread. Future growth will primarily come from widening and improving internet access in developing markets, thanks to increasingly affordable smartphone models and government investments in mobile broadband coverage.

Mobile phones are the primary device used by new internet users to go online and to access social media. Last year, 74.7% of mobile phone internet users worldwide used their device to access social media. Overall social media use is primarily a mobile activity, and 82.5% of social network users worldwide used a mobile device for access at least once a month.

Meanwhile, nearly 594 million people worldwide used Instagram regularly in 2017, representing about a quarter (24.0%) of total social network users. Penetration among social network users and the population as a whole was highest in North America and Western Europe.

Facebook is by far the top social network in the world. More than 1.54 billion people, or 62.2% of social network users, went on Facebook at least once a month in 2017.

These estimates are drawn from eMarketer's latest report, "Worldwide Social Network Users Update: eMarketer's Estimates and Forecast for 2016–2021, with a Focus on Instagram." The report includes eMarketer’s forecast for social network users, Facebook users and Twitter users worldwide, as well as our first estimates for Instagram users worldwide. eMarketer PRO subscribers can access the full report here. Nonsubscribers can learn more here.

In the latest episode of "Behind the Numbers," analysts Cindy Liu and Debra Aho Williamson break down eMarketer's new estimates for Instagram use around the world. How has the audience shifted, and what comes next?