What is Google Page Rank?
The co-founders of Google, Larry Page and Sergey Brin, describe Google Page Rank as a tool designed to rank a website that is listed in the Google search index. A Pagerank of a web page is given on a scale of 0-10. 0 is the lowest possible score for a website and conversely a 10 is the highest score possible. A high Pagerank is defined by the amount, importance(PageRank) and relevance of web pages that link to the web page in question. When a web page links to another web page, Google consider that to be a vote for the page in question and therefore of some importance. There is a formula associated to how PageRank is calculated but for the purposes of this article it is too indepth, but if you are interested in the theory behind PageRank (PR) then a quick search on Google will provide fruitful.
What is Alexa Rank?
The Alexa Rank is different to Google PR; Alexa rank websites based solely on traffic to the website. Alexa rank websites in descending order towards 0, where the most highly visited website on the Internet is given a rank of 0. At this point in time the top three ranked websites (most visitors) on Alexa are, 0 - Yahoo, 1 - Google and 2 - MySpace. According to Alexa these 3 websites get the most traffic on the Internet. Alexa Rankings vary from 1 to a billion. Every web site in the world is included in the Alexa Rank, so the scale on your Alexa ranking is constantly changing in relation to other websites on the Internet.