The explosion in the number of Internet-capable mobile devices will grow with the number of mobile users seeking access to online services, which could top 900 million by 2013, IDC said. Some of the popular online activities through mobile devices today include accessing news and search engine Web sites, downloading multimedia files and exchanging e-mail and instant messages.

Consumers will make a larger number of online purchases using mobile devices, which could lead to growth in e-commerce activity. Businesses will also look to increase mobility of employees by providing access to business applications and corporate e-mail systems. But at some point, the lines could blur as mobile devices get utilized for corporate and personal activities, said John Gantz , chief research officer at IDC.

Close to 450 million users sought access to the Internet through mobile devices this year, IDC said. That number could grow as Internet-capable mobile phones, smartphones and other wireless devices become affordable.

The number of mobile Internet users will grow as the number of worldwide Internet users increases. A total of 1.6 billion people accessed the Internet this year, and the number could reach over 2.2 billion users in 2013. More than 1.6 billion devices, including mobile devices, PCs and gaming consoles, were used to access the Internet this year, and that number could top 2.7 billion by 2013.

The U.S. had the largest number of fixed and mobile devices connected to the Internet, but China led in the number of Internet-connected mobile devices at around 85 million.

China also had the largest total number of Internet users, with 359 million this year, and the number is expected to grow to 566 million by 2013. The U.S. had 261 million Internet users in 2009, which could reach 280 million in 2013. The number of Internet users in India could double between 2009 and 2013, according to IDC.