URL Suffix List
You can use the end, or suffix, of a domain name to help you judge the validity of the information and identify the potential bias of a website.
Remember, this strategy is only a guideline. People may purchase domains that do not necessarily reflect their actual purpose.
.com - Commercial Site (commercial sites may vary in their credibility)
.gov - a U.S. government site
.org - an organization, often a nonprofit site
.edu - a school or university site in the United States (Determines whether the school source is K-12 or university and whether the page was written by a student or a scholar.)
.ac - an educational institution, like .edu
.mil - a U.S. military site
.net - a networked service provider, an Internet administrative site
.museum - a museum
.name - an individual Internet user
.biz - a business
.info - a site with general information
.pro - a site representing a professional
.coop - a cooperative
.store - a retail business
.aero - a site from the aviation community
.int - an international institution
~ - (the tilde) a personal page
Another way to establish the credibility of a site is to perform a Link Check.
You use a search engine like AltaVista or Google to see which other sites have chosen to link to the site you are evaluating. In the search box, enter: link:http://siteaddress.