How are websites ranked by popularity?
Alexa ranks sites based on tracking information of users of its Alexa Toolbar for Internet Explorer and Firefox and from their extension for Chrome. Hence the page is only ranked between users who have these sidebars installed and may be biased if specific audience is reluctant to do this (Windows Defender has classified the sidebar as malware while it assigns it to Trojans). Also, the rank is based on three month data and takes a long time to reflect changes in content that may happen after the domain has been sold. Finally, low ranks cannot be accurate not just because of the lack of data but also because of statistic laws related to the long tail distribution.
There is some controversy over how representative Alexa's user base is of typical Internet behavior, especially for less trafficked sites. In 2007 Michael Arrington provided a few examples of relative Alexa ranking known to contradict data from comScore, including ranking YouTube ahead of Google.
On April 16, 2008, many users reported dramatic shifts in their Alexa rankings. Alexa confirmed this later in the day with an announcement that they had released the new Alexa ranking system, claiming that they now take into account more data sources "beyond Alexa Toolbar users".
How can I get a higher ranking?
Web traffic can be increased by placement of a site in search engines and purchase of advertising, including bulk e-mail, pop-up ads, and in-page advertisements. Web traffic can also be increased by purchasing non-internet based advertising.
If a web page is not listed in the first pages of any search, the odds of someone finding it diminishes greatly (especially if there is other competition on the first page). Very few people go past the first page, and the percentage that go to subsequent pages is substantially lower. Consequently, getting proper placement on search engines is as important as the web site itself.