Plagiarism is a very serious offense in academia, with consequences ranging from failing your essay to getting suspended from your course. Even if not intending to, it can be easy to mistakenly plagiarize content from other papers.
Here are some sure ways to avoid falling into that trap.

Understand what plagiarism is

Plagiarism means falsely representing someone else’s work as your own. What constitutes someone’s work may be ideas, theories, results, and the words and sentences used to express those. Note that it’s possible to self-plagiarize, though it isn’t so severely punished.

Cite your sources

Building up on other people’s research is an entirely normal (and expected) way of doing your own. But make sure to include the names of authors whose ideas and words you mention in your paper. And not only in your ‘References’ section at the end, but in the body of your text.

Signal direct quotes

If you want to use someone else’s words or sentences verbatim, use quotation marks. These clearly signal to the reader that the words aren’t your own. Note that direct quotes should be a reasonable length, and used sparingly.

Make use of paraphrasing

Paraphrasing (i.e. expressing meanings with different words) helps you convey an author’s ideas without resorting to direct quotes. But be careful: you should still acknowledge their source, by mentioning the author name(s) as part of your indirect quote. For help with paraphrasing, check out Writefull’s Paraphraser.

Try a plagiarism checker

If you feel anxious about accidental plagiarism, look up plagiarism checkers online. These will parse your text and compare it to a database to automatically detect copied content, saving you a great deal of time and stress!