What is Alexa rank ? How accurate is it ?

It is a subsidiary company of Amazon.com which ranks different websites based on the traffic for that site.

The Alexa rank is taken as standard on many advertising networks for accepting new publishers e.g. Text Link Ads, Pay Per Post etc.

How "Accurate" is Alexa rank ?

No lets first see how Alexa works and how does it ranks sites.

Alexa ranks websites based on the visits by internet users using Alexa Toolbar to any site. The important point is Alexa does not take into account the visits by users not using Alexa Toolbar.

I just compared two of my sites, one site was related to Bollywood and other related to Blogging and Webmaster resources. As per Google Analytics daily visitors for my Bollywood related site was 2000 and that for Blogging and Webmaster resources related site was 1300. But the Alexa rank for my Bollywood site was >100,000 and that for Blogging related site was between 80,000-85,000.

Now lets see why is it like this - it is less likely that visitors for Bollywood site having Alexa Toolbar installed as compared to visitors for Blogging site who are mostly webmasters and having Alexa Toolbar installed. So although my Bollywood site get more visitors but still have less Alexa rank as compared to Blogging site.

Thus you can see how 'Accurate' is Alexa rank.

One more fact about Alexa tooolbar - it is considered as a spyware, adware software by many Antivirus programmes. McAfee detects Alexa toolbar as an adware, 'Potentially Unwanted Programme'.

Many other security softwares also detect Alexa Toolbar as an adware and spyware.

But still many sites consider Alexa rank as standard.