alexa is an internet information company.they give ranking for all website and trace users of the website.it was founded in 1996.it is part of amazon.com.they also provide advertisements and toolbar,widgets for website.alexa rank is likely to google's page rank.but the difference is page rank from 0 to 10.but alexa rank from crores to 1.alexa rank will be very useful in internet online marketing field.





learn more...http://en.wikipedia.org/wiki/Alexa_Internet,http://www.alexa.com