Credentials: plural noun. The abilities and experience which make someone suitable for a particular job or activity, or proof of someone's abilities and experience
Cambridge Dictionaries Online, 2003
Do you believe everything you read? Knowing more about an author can help you judge her or his credibility.
If you were writing about the relationship between human activity and the temperature of the earth, whose work would you choose to include in your paper? Look for clues that suggest their level of expertise and/or bias.
In terms of evaluating an author, credentials include degrees received, titles held, professional affiliations, years of activity in a field, publication history, fields of inquiry, and the characteristics of publications in which their work has appeared.
Similar to judging an author's credentials, knowing more about a publishing company can help you understand their potential biases. Keep in mind that publishing standards vary for each publishing house. XYZ Publishing may print anything that will bring a profit, whereas H. University Press may screen all information they publish to ensure the validity of the content, protecting their reputation.
There are several general categories of publishers: