Some Important Disclaimers
The traffic data are based on the set of Alexa users, which may not be a representative sample of the global Internet population. Known biases include (but are likely not limited to) the following:
Our users are disproportionately likely to visit alexa.com, amazon.com and archive.org, and traffic to these sites may be substantially overcounted.
The Alexa Toolbar works only with the Internet Explorer browser. Sites frequented mainly by users of other browsers will be undercounted. For example, the AOL/Netscape browser is not supported, which means that Alexa collects little data from AOL users, and our traffic to aol.com is likely lower than it would be for a more representative sample.
The Alexa Toolbar works only on Windows operating systems. Although a large majority of the Internet population currently use Windows, traffic to any sites which are disproportionately visited by users of other operating systems will be undercounted.
The rate of adoption of Alexa software in different parts of the world may vary widely due to advertising locality, language, and other geographic and cultural factors. For example, to some extent the prominence of Korean sites among our top-ranked sites reflects known high rates of general Internet usage in South Korea, but there may also be a dispropotionate number of Korean Alexa users.
In some cases traffic data may also be adversely affected by our "site" definitions. With tens of millions of hosts on the Internet, our automated procedures for determining which hosts are serving the "same" content may be incorrect and/or out-of-date. Similarly, the determinations of domains and home pages may not always be accurate. When these determinations change (as they do periodically), there may be sudden artificial changes in the Alexa traffic rankings for some sites as a consequence.
The Alexa Toolbar turns itself off on secure pages (https:). Sites with more secure page views will be under-represented in the Alexa traffic data.