Whenever you use information from someone else in your paper—whether it's an idea or a word for word quotation—you need to acknowledge the source. This has two parts:
Appropriate use of in-text citations which tell the reader where the information originated.
A list of sources consulted that tell the reader exactly where they can find the information on their own.
The Ohio University Student Judiciaries page Academic Misconduct describes the consequenes of plagiarism for students at OU. While the consequences are serious, there are many resources available to help you avoid plagiarizing in your research paper:
From the Online Writing Lab (OWL) at Purdue University: