The explosion in Internet-enabled devices will coincide with an equally dramatic increase in mobile Internet users worldwide, IDC said. The number of users worldwide will more than double by the end of 2013 from 450 million this year.
"With a wealth of information and services available from almost anywhere, Internet-connected mobile devices are reshaping the way we go about our personal and professional lives," IDC researcher John Gantz said in a statement. "With an explosion in applications for mobile devices underway, the next several years will witness another sea change in the way users interact with the Internet and further blur the lines between personal and professional."
Today, the most popular online activities of mobile Internet users are similar to those of people accessing the Web from a PC: using search engines, reading news and sports, downloading music and video, and sending/receiving e-mail and instant messages. Over the next four years, the fastest growing applications will be making online purchases, participating in online communities, and creating blogs, IDC said.
On the corporate side, accessing online business applications and corporate e-mail will grow rapidly among businesses' mobile workforce, the researcher said.
IDC also reported in its new Marketplace Model and Forecast report that more than a quarter of the world's population, or 1.6 billion people, used the Internet in 2009 on a PC, mobile phone, video-game console, or other device. By 2013, that number is expected to rise to 2.2 billion.
China has the most Internet users of any country, with 359 million this year. The United States in comparison had 261 million, IDC said. By 2013, those numbers will increase to 566 million and 280 million, respectively.
The U.S. in 2009 had the highest total number of devices connected to the Internet, but China was the leader in the number of mobile online devices with almost 85 million, the researcher found.
In the area of e-commerce, more than 624 million Internet users globally this year will spend nearly $8 trillion online, both business-to-business and business-to-consumer. By 2013, the amount spent will rise to more than $16 trillion, IDC said.
Spending on Internet advertising, meanwhile, will total nearly $61 billion this year, slightly more than 10% of all ad spending across all media. This share will reach almost 15% by 2013 to $100 billion worldwide, IDC predicted.