With every source you find - regardless of where it comes from - you MUST assess its quality to determine if it is worthy of being included in your research. Generally speaking, academic papers are looking for you to first consult scholarly, peer-reviewed research from reputable publishers.
*Note that you should always follow the instructions given to you by your professor. There are certainly times/places when using other materials has value to scientific research!
For every resource you find, a good place to start is with the CRAAP test! The best researchers will use lateral searching techniques when assessing a resource - turning to sources outside of just that specific piece of information to assess its credibility. Ask yourselves these questions about the resource you have found.
When was the resource published?
Is this the most up-to-date information available?
Does this matter for your topic? Or are you researching something that could benefit from using some older resources?
Even if it is up-to-date, is the information going to answer your research question?
Is the information going to expand upon what you already know, or offer a new perspective on the subject?
Is the scope of the material appropriate for your needs? An entire book or doctoral thesis may not be appropriate for a small assignment, for example.
Is there a listed author(s)?
Are they credible? Do they have the credentials, qualifications, or experience to discuss such a topic?
Do they cite their sources? Are they citing other experts?
Do they tend to be neutral? Or do they tend to have an agenda in their writing?
Are the publication and the publishing company reputable? Does the publisher actually exist, or have they just created a website that makes it seem so? Beware of shady publishers that will publish anything for a fee, or who don't seem to have an actual building or staff.
Has the resource undergone peer review? Most publications that peer review will make it very obvious that they do so.
Are you able to independently verify that the information is correct?
Can you find another source that confirms this information that is also reputable?
Are there any noticeable errors or questionable content?
Do the conclusions reached seem reasonable? Or does it seem like they are jumping to conclusions?
Why was this information written and made available to you?
Was it written for academic purposes? To entertain or shock you? To sell you something? To convince you of a political standpoint? etc.
Is it biased or promoting an agenda?
Is the author writing for some purpose that benefits themselves?
Predatory publishers, also known as predatory journals, are publications that will accept virtually any article as long as they are paid to do so. The result of this is poor quality scholarship that is made widely available under the guise of having merit. Pay attention to the following warning signs when assessing the quality of a publication.