Alexa, owned by Amazon company, is an international meter operates from 1997. In their search, not only provides results about classification of the sites, but also an aspect of the image Web ('screenshot') and a short questionnaire for assessing the page.

Its measurements are the most respected Internet, many Sponsors and advertisers take into account the position in that ranking to promote and sell their products. To explain it better, a way to measure the audience of each website in the world.

For the user, Alexa is presented as a floating navigation bar that appears when you're out surf (You can remove or hide when he wants). For each site you visit, Alexa offers a list of other possible destinations constituted on the basis of collection of sites that other users have been directed from the page where you are.

This tool is not a substitute for search engines like AltaVista and HotBot or Yahoo type directory. It is a supplement that helps to find useful ways and often unexpected. It also offers information on the name of the company that maintains the site visit, address and telephone.

How it works Alexa?

To elaborate this classification, 'alexa.com' collects two types of information: the number of unique users who access a page and the number of pages views, ie the total number of times a user requests a particular web address. To avoid the production of pages view by automatic engine, alexa.com consider several requests in the same direction by the same user in the same days as a single page view. With this process, has alexa.com consolidated its 'ranking' as the most objective and reliable Internet and reflects the tastes and preferences of users at world.

The advantages are: first, the bar provides the information traffic of each site you visit, as well as data person or company responsible for each Site. You have to take also that each visit you make will put points on the ranking .