First, there are many different types of domain names.
.com (these are commercial sites)
.edu (these are educational sites)
.gov (these are government agencies sites)
.org (these are usually non-profit organizational sites like churches, charities etc).
Now let us talk about credible web sites. Credible web sites have what are known as Ethos which translates to Ethos = Credibility. They offer ways to look for the credibility of the author/or publisher. Authoritative sites may have an opinion or slants that are based on verifiable facts. Authoritative = Credibility = Ethos
What you need to do is go down to the bottom of the sight of the home page to find out who is the publisher of the site. There is also other information that you can find about a web site in its bottom page. The publisher must offer proof by describing its media reach and by offering other names and data. Many sites are not authoritative and not all of their sources are credible. So look out and do your research so the information that you find on the internet is credible.
In addition, the Ashford Online Library is a great tool that helps students who are doing research on a particular subject. I downloaded, and printed the twenty-page tutorial and I found it was easy