Plagiarism: The cardinal sin of writing and how to avoid it: Citation Basics

You need to cite work in your research in the following situations: 

• Direct quote: If you include a sentence or passage directly word for word from another source of material, you need to put quotation marks around it and cite the work.
• Paraphrasing: This is a restatement of someone else's ideas in your own words. Doing this may help the flow of your own work and demonstrate that you understand what the author was portraying but it does not excuse you from citing the author's work. Paraphrasing is generally around the same length as the original work.
• Summarizing: This is taking the author's general ideas and putting them into a more concise format in your own words. Once again, the work needs to be cited.
• Facts and data: If the facts and data you are using in your work are from a specific study or scientific experiment and are not generally accepted and widely known, you must cite the work.

Situations where you don't need to cite

• Common knowledge: Commonly known facts such as historical dates and basic summaries, facts that are generally known and can be found from many sources, commonly known scientific facts that are not controversial or in dispute, and commonly known sayings and expressions. 
• Your own ideas or opinions: If you are drawing conclusions from research that the author did not draw, state that they are your own or present them as such. However, if you use charts or data that the author used to reach this conclusion, you must cite the data that you used to draw the conclusion. 

 BUT, IF ARE EVER IN DOUBT, CITE!!!