Your assignments should result from your own hard work. That said, your work is not limited to just your views and opinions. Instead, it should be developed by thinking about the research and ideas you have read and engaged with.
Be honest about anyone else's ideas that you have used or mentioned in your work and acknowledge these sources clearly.
Whenever you directly copy the words of another author (quoting) or put their ideas into your own words (paraphrasing) you must acknowledge that you have done so, with a reference.
Peer-review is a rigorous vetting process. For example, a Professor at University of Sussex had his 8,000 word paper peer-reviewed upon submission to a scholarly journal, which resulted in 3,000 words worth of comments from four reviewers, one sub-editor, and one editor. Consequently, peer-reviewed articles are often held in higher regard than those which aren't.