"As Internet usage outside the U.S. has grown rapidly from a small base, the U.S. share of the world's online population has fallen from 65 percent to less than 25 percent in the last 10 years," said Bob Ivins, managing director of comScore Europe. "The fact that more than three-quarters of the traffic to Google, Yahoo!, and Microsoft is now coming from outside of the U.S. is indicative of what a truly global medium the Internet has become."

Page Views and Engagement of Non-U.S. Users

Although international users represent a larger proportion of the overall traffic to many of the top-ranked U.S. sites, comScore data show that U.S. users are more engaged with many of these properties, as indicated by the slightly higher proportion of pages viewed by U.S. users. Two notable exceptions are (1) Google, whose non-U.S. users represent 79.8 percent of total traffic to the site but account for a higher share of page views (89.1 percent), reflecting the higher number of searches conducted per searcher in International markets; and (2) Lycos, which has non-U.S. users representing 39.4 percent of its visitors while drawing a disproportionately higher share of pages from outside the U.S. (73.3 percent).

"The high proportion of visitors and page views from outside the U.S. represents a solid growth opportunity for U.S.-based ad-supported properties, which currently derive most of their revenues from domestic online advertising," Ivins added.

* Excludes traffic from public computers such as Internet cafes or access from mobile phones or PDAs.

Sites with Audiences Concentrated in the U.S.

Some sites do not attract a substantial percentage of international visitors. Examples include U.S.-based, telecommunications/ cable companies such as Verizon and AT&T, media entities including Fox (owners of MySpace), New York Times Digital, and CBS, and major U.S. retailers, banks and airlines such as Target, Wal-Mart, Bank of America and United.