Peer Review is a process where journal articles are vetted by experts in the subject area before publication. Experts judge the merits of an article on methodology, research, relevance, and other factors. The goal of Peer Review is to ensure that only high-quality, relevant articles are published in a particular journal.
Peer-reviewed articles are typically heavy on text, beginning with an Abstract and ending with References or Bibliography. There will be no advertising or sidebars mixed in with the article, as often happens in a popular or trade magazine.
In EBSCOHost databases you can choose Limit To Scholarly (Peer Reviewed) Journals:
Please note that under the rubric of "Scholarly Journals", some articles may come up that are letters to and from the editor, administrative matters and other pieces that are not peer-reviewed. Always look at the article's structure and content.
A "think tank" is an organization that conducts research, issues publications and offers policy opinion in particular areas of interest. Think tanks can be politically biased. For example, Heritage Foundation is a conservative organization; the Cato Institute has a heavy libertarian bent, and the New Policy Institute is progressive. The biases of a host institution exert a strong influence on its employees and publications, so you should always take that into account when reading and using research from the think tank arena
When conducting research, it's important to verify the credibility of a work's author (or authors). Is the author a recognized expert in the field on which they're writing? Do they have a Ph.D. or other advanced degree in the subject? Do they have a body of work representing a breadth and depth of knowledge in the area you're researching?
Often within a database or article itself, you'll see author credentials listed. You can also search for the author on the Internet (using Google or whichever search engine you prefer) to see if they have a curriculum vitae or list of published works and professional activities.
Certain databases may show how many times an article has been cited. Usually, a high citation rate means the author has been influential in their field. See for example the Times Cited feature in some EBSCOhost databases, and Web of Science.
Beware bias: If you're looking at a web page, take a look at the website. Observe the URL. What organization is running the website? Is it a political organization, think tank or other entity that could have a strong bias? This will influence what is published and how works are edited.
If no author is listed for an article, be cautious in using this as a source. You should ask yourself, why wouldn't an author want to have her or his name attached to this piece?
If your assignment allows use of non-scholarly sources such as web pages, be sure to check them carefully.
Is a date listed? How old is this information? If the page was published some years ago, have there been any updates? If not, the information may be out-of-date.
Is an author listed? What credentials and expertise does this person have?
Are any references listed? What is the quality of those references? (i.e., links to conpsiracy websites vs. references to scholarly journal articles).
What organization is running the web site? What biases do they have? What is the main purpose of the website?
Does the website sell products or services, or run specific advertisements for other companies? If so, take that into account as it probably introduces biases into what is published and how it's edited.
How professional and well-designed is the website? Please note this can be tricky as certain well-regarded websites may look as if they're stuck in a time warp; judicious Googling may help you determine when this is the case. See contrasting examples: Snopes vs. The World's Worst Website Ever.
Beware satirical or parody websites. There are some websites which look reasonably "real" but publish satirical (untrue) articles or otherwise pretend to be a serious website when it's really a parody. See for example The Onion.