Forty percent of the world's population will have access to the Internet by 2015, according to a new forecast released this week by market research firmIDC. But the way they access it is shifting drastically, particularly in the United States, Western Europe, and Japan, as media tablets and smart phones begin to take the place of the traditional PC.

In fact, in the United States, more people will access the Internet through their mobile devices than through wired connections by 2015, IDC reported.