Google PageRank (PR) :

PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page's value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at considerably more than the sheer volume of votes, or links a page receives; for example, it also analyzes the page that casts the vote. Votes cast by pages that are themselves "important" weigh more heavily and help to make other pages "important." Using these and other factors, Google provides its views on pages' relative importance.

Of course, important pages mean nothing to you if they don't match your query. So, Google combines PageRank with sophisticated text-matching techniques to find pages that are both important and relevant to your search. Google goes far beyond the number of times a term appears on a page and examines dozens of aspects of the page's content (and the content of the pages linking to it) to determine if it's a good match for your query.

Alexa ranks sites based on visits from users of its Alexa Toolbar for Internet Explorer and from integrated sidebars in Mozilla and Netscape. In addition to their own statusbar extension, Sparky (released July 2007), there are several third-party extensions for Mozilla Firefox:

* SearchStatus shows Google PageRank and Alexa TrafficRank
* About This Site Firefox plug-in that shows metadata from Alexa TrafficRank.

There is some controversy over how representative Alexa's user base is of typical Internet behavior. If Alexa's user base is a fair statistical sample of the Internet user population (e.g., a random sample of sufficient size), Alexa's ranking should be quite accurate. In reality, not much is known about the sample and possible sampling biases. Alexa itself notes several examples. A known source of bias is the self-selecting, opt-in nature of Alexa traffic tracking software installation, but the significance of this bias on rankings is not reported.

Link Popularity : ( Check your link popularti from Google , Yahoo ... )

Link popularity is a measure of the quantity and quality of other web sites that link to a specific site on the World Wide Web. It is an example of the move by search engines towards off-the-page-criteria to determine quality content. In theory, off-the-page-criteria adds the aspect of impartiality to search engine rankings. Link popularity plays an important role in the visibility of a web site among the top of the search results. Indeed, some search engines require at least one or more links coming to a web site, otherwise they will drop it from their index.

Search engines such as Google use a special link analysis system to rank web pages. Citations from other WWW authors help to define a site's reputation. The philosophy of link popularity is that important sites will attract many links. Content-poor sites will have difficulty attracting any links. Link popularity assumes that not all incoming links are equal, as an inbound link from a major directory carries more weight than an inbound link from an obscure personal home page. In other words, the quality of incoming links counts more than sheer numbers of them.

Domain Age :

One of the many factors in Google's search engine algorithm is the age of a domain name. In a small way, the age of a domain gives the appearance of longevity and therefore a higher relevancy score in Google.

Driven by spam sites which pop up and die off quickly, the age of the domain is usually a sign whether or not a site is yesterday's news or tomorrow's popular site. We see this in the world of business, for example. While the novelty that may go with a new store in town brings a short burst of initial business, people tend to trust a business that has been around for a long time over one that is brand new. The same is true for websites.