Your research paper represents your ideas in conversation with the ideas in your sources. To be fair and responsible, you must acknowledge your debt to the writers of those sources. When you acknowledge your sources, you avoid plagiarism, a form of academic dishonesty.
Three different acts are considered plagiarism: (1) failing to cite quotations and borrowed ideas, (2) failing to enclose borrowed language in quotation marks, and (3) failing to put summaries and paraphrases in your own words. Definitions of plagiarism may vary; it’s a good idea to find out how your school defines and addresses academic dishonesty.