Plagiarism is the presentation of another person's work, ideas, or creations as your own, without acknowledging where those ideas came from. In other words - you take credit for someone else's work.
THIS IS CHEATING!!
What constitutes plagiarism?
If you have used someone else's work without acknowledging your source, you have plagiarised.
There are a number of different referencing systems used in academic writing. Two most common types are:
Author-date systems, such as the Harvard System
Number systems, such as the Chicago System