Most academic writing cites others' ideas and research, for several reasons:
Different academic disciplines prefer different citation styles, most commonly APA and MLA styles.
Ask your instructors which citation style they want you to use for assignments.
To avoid plagiarism, provide a citation for ideas that are not your own:
You do not need to cite common knowledge (ex. George Washington was the first President of the United States) or proverbs unless you are using a direct quotation. When in doubt, cite your source.