Plagiarism is using another person's work without giving proper credit. "Proper credit" means using the correct citation style and format for the type of citation and clearly indicating in your writing that the work is not your own.
Examples of Plagiarism:
10 Types of Plagiarism [Video]. (2012, November 16). Retrieved March 10, 2014, from http://www.youtube.com/watch?v=EF5eFeJMplA