Peer-review is the process that articles undergo before they are published in an academic journal. The peer-review process helps to "validate academic work" and "helps to improve the quality of published research." This process is usually done in a double-blind process where neither the author nor the reviewers know each other are to allow for more impartial reviews. You can use your "refine results" limiters to search for peer-reviewed work.
Elsevier. (n.d.). What is peer review? Retrieved on September 29, 2020, from https://www.elsevier.com/reviewers/what-is-peer-review
Books are not commonly peer-reviewed because the process would take too long. Despite their lack of peer-review, they contain valuable scholarly content. You can use your "refine results" limiters to search for scholarly books.
If you are trying to decide whether a book is considered "scholarly" look at:
the publisher (does it come from a university or academic press?),
the author (what are their credentials? where do they work?),
check if there are lots of references (this shows scholarly conversation),
and make sure the work is current (check publication date, what has been published since the work you are looking at?).
Original research is when an author is writing about the research/study/experiment that they conducted. Articles reporting on original research usually follow a similar format. You will typically find a literature review, methods section, results section, conclusion, and discussion. Most databases will not let you filter results for original research so you will have to critically assess the article and judge whether it is original research for yourself.
Grey literature is not peer-reviewed and is usually not considered scholarly (always double-check with your instructors), but it can hold valuable good-quality information. Grey literature is created and/or distributed by governments, scholars, and experts and is therefore considered credible.
Grey Literature Formats:
Doctoral dissertations and Masters theses,
NorQuest College Library. Learn to research: Grey literature [LibGuide]. Retrieved on September 29, 2020, from htps://libguides.norquest.ca/learn_to_research/grey_literature
You might be required to use other types of sources in your research. Materials like art prints, music scores, movies, audio and visual clips, and photos can all contribute to your research. While these sources are not considered scholarly they are still good inclusions into research as supporting documents or examples.