The following are examples of plagiarism, scaled from the mildest to most serious offences, which may be collectively known as "The Plagiarism Continuum" (Walker, J. (1998) "Student Plagiarism in Universities: What Are We Doing About it?" Higher Education Research and Development, 17, 1, 89-105)

"Sham paraphrasing"
Material copied verbatim from text and source acknowledged but represented as paraphrased.

"Illicit paraphrasing"
Material paraphrased from text without acknowledgement of source.

"Other plagiarism"
Material copied from another student's assignment with the knowledge of the other student.

"Verbatim copying":
Material copied verbatim from text without acknowledgement of the source.

"Self-plagiarism" or "recycling"
Same assignment submitted more than once for different courses.

"Ghostwriting"
Assignment written by a third party and represented by student as own work.

"Purloining"
Assignment copied from another student's assignment or other person's paper without the person's knowledge.

Is working together plagiarism?

There are occasions when it is perfectly acceptable (and expected) for students to work together on an assessement task (such as group projects) and occasions when it is definitely unnaceptable (such as exams). In many cases, however, the guidelines aren't so clear.

While learning from peers is encouraged at Macquarie University, students also need to be able to show independently that they have an adequate understanding of the topics covered in the assessment task. If the lecturer thinks that any two assignments are too alike, the students involved may be accused of plagiarism, even though one wasn't copying from the other. The lecturer may not consider the fact that the students worked together a valid excuse

In general, while discussing ideas and helping other students is encouraged, working together on a whole assignment is innapropriate unless explicitly stated by the lecturer. Once your fingers hit the keyboard or pen hits the page, the work should be your own.