What does the author know about the subject?
Is the author an expert in this field of research? Does the author have direct personal experience with the subject matter? The answers to these questions can help you determine the author's expertise in the area they are writing about.
Where to find
Articles may or may not provide author credentials. Popular articles may include them near the author's name, usually at the beginning or end of the article. You can Google an author to learn more about their expertise on a topic. Scholarly articles are more likely to list information about the author's institutional affiliation, often on the first page of the article:

Books usually contain information about the author on the jacket, the back of the book, or within the first few pages:

Websites, like articles, may or may not provide credentials. If they are included, they can commonly be found at the top or bottom of a page, or sometimes the author's name is a link leading to their credentials.
