Google, Microsoft top Nielsen/NetRatings Web site lists

The latest figures from Nielsen/NetRatings on the most popular Web sites in the U.S. are in, and Microsoft and Google are on top.

But that's a simplification because there is more than one list and several metrics can be used to gauge popularity.

For instance, Nielsen/NetRatings has two Top 10 lists (PDF). One list is for the top Web sites by parent company, with "parent company" defined as "a consolidation of multiple domains and URLs owned by a single entity." The second list is for the top brands, with "brand" being defined as "a consolidation of multiple domains and URLs that has a consistent collection of branded content."

Microsoft is at the top of the parent company list and Google leads the brand list.

The two different lists also break out the unique audience for each entry as well as the time spent per person on the sites. Google is first or second on the lists according to audience, but when it comes to measuring time spent per visitor the company ranks a mere sixth, while AOL is ranked top brand under that metric. This was expected when Nielsen/NetRatings announced this summer that it would include the new measurement in its rankings.

Nielsen/NetRatings also released a list of the top 10 online advertisers in the U.S. based on estimated spending. Low Rate Source, which provides online mortgage quotes, was at the top of that list, spending more than $51 million. That firm was followed by comparison shopping site NexTag; credit report agency Experian; InterActive Corp., which owns Ask.com, TicketMaster and Lending Tree; Countrywide Financial; AT&T; Netflix; Verizon; job site Monster.com; and Privacy Matters, which offers credit report services.

Nielsen/NetRatings has several ways of determining the Web's most popular sites.

(Credit: Nielsen/NetRatings)