Plagiarism can take many forms. Here are the most common types:
Accidental plagiarism
Many students accidentally plagiarize by forgetting a citation, forgetting quotation marks, or too closely copying the words of someone else. Proof read your work carefully to be sure that you have included a citation and quotation marks whenever necessary.
Directly copying another's work
Taking someone else's work and copying it word-for-word without citing the original source or using quotation marks is plagiarism. This includes copying and pasting text from the web.
*Almost* directly copying another's work
Even if you do not take a complete sentence of someone else's writing, using the same phrases or replacing specific words with synonyms is still plagiarism. If you want to paraphrase someone's work, you need to make the same point as them by using your own words. This is usually done to make their point more clear. Paraphrasing still requires a citation.
Submitting your own work for another class
Resubmitting work (partial or whole) that you submitted in another class without permission from your current or previous instructor is cheating. For example, if you wrote a paper and turned it in for a grade, you cannot submit the same paper for a different class, even if it is on the same topic.
Having someone else complete your assignment
Do not turn in an assignment that your friend, parent, coworker, or another student completed for you. Your assignments should be your own, original work. If you complete an assignment with the help of a tutor or another classmate, let your instructor know.
Avoiding plagiarism is not hard, but it can be intimidating. The resources below offer tips for how to avoid it.
Websites:
Purdue OWL: Avoiding Plagiarism
Avoiding Plagiarism: Quoting and Paraphrasing
Five Most Effective Methods for Avoiding Plagiarism
Videos:
MyBib: Fully automated bibliography maker builds works cited/references pages in several different citation styles.
NOTE: STCC Library's Citing Sources Guide is also helpful when working the MLA, APA or AMA formats.