Authority
Authority is important in determining the credibility of a website because it establishes who is in charge of the site, who wrote the information covered there, and more. It is important to look at the background information of an author so that you can understand where the author's potential biases might lie, how the author knows this information, etc.
In this case, "author" referes to an individual, a company, or an institution.
Here are some questions, written by Susan A.Gardner, Hiltraut H. Benham, and Bridget M. Newell in their 1999 article "Oh, What a Tangled Web We've Woven! Helping Students Evaluate Sources,” published in English Journal, that you should answer when determining the authority of a source:
Is the author's name listed?
Why is this important? If you know who the author is, you can more easily look up the author and see what else the author has written. If the piece is anonymous, it may not be as reliable because you have no way of finding out if the author is an expert in the field about which they are writing.
What are the author's credentials? Do these identify the author as an authority in the field?
Why is this important? Credentials, or the title, such as professor, doctor, specialist, etc. or degree, such as MA, MS, MD, PhD, etc. show that the author is recognized as an authority in the field, either through education (by earning a degree) or by job title or job experience.
Is the author's institutional affiliation listed and linked to the home page of that institution?
Why is this important? Institutional affiliation means what school, business, department, professional organization, etc. the author belongs to. If the author belongs to one or any of these institutions, there should be a link to said institution's site. This helps determine credibility because an author who is a recognized member of a respected institution has been vetted by that organization as an authority on a particular subject.
Is the relationship between the institution and the author clear?
Why is this important? If there is a link to the institution but no explanation is made as to the connection the author and the institution share, then you may have to look around both sites to see how the author is vetted by or affiliated with this institution. If you cannot find this information, the author may be lying or misrepresenting their affiliation with the institution, which would make the author seem less credible.
Does the author list an address (e-mail or snail mail) or phone number for contact?
Why is this important? Authors who are authorities in their subjects should welcome inquiries from others. If the author includes no way to contact them, the site may not be as reliable as there is no easy way to ask the author questions about the source of their information.
Is there a link to the author's biographical information?
Why is this important? It is important to know as much information as possible about an author to see if they are knowledgable in the field. For example, if an author is writing about biomedical engineering and his biography states that he has an MA in English Literature, is he as reliable a source as someone who holds a PhD in Biomedical Engineering? The answer is no.
Most of this information can be found in the About Us or the Contact Us link on a webpage. If your source is an article in a newspaper, online magazine, blog, etc., information about the article's author can be found at either the beginning or end of the article while information on the newspaper, magazine, etc. can be found in the About Us or Contact Us link on a webpage.