Briefly, plagiarism is the unacknowledged presentation of the work of others as one's own. To represent such work as self-created is dishonest and academically worthless. We hope that this will help to clarify what plagiarism is, and how to avoid it in psychology papers you write. The main reason for citing other works in a paper is to tell readers about previous research on the topic and to let them know where you got your ideas from. If you put someone else's words or ideas down without acknowledging the source, that is a form of stealing.
Most universities have very severe penalties for plagiarism of any kind.
The way to avoid even the suspicion of plagiarism is to give credit where it is due. If you are using someone else's ideas, acknowledge them, even if you have changed the wording or just summarized the main points. Don't be afraid that your paper will seem weaker if you acknowledge the ideas of others. Besides, citing the sources shows that you are aware of what has already been published. Another and more serious form of plagiarism is to take not only another person's ideas, but his or her actual words, without acknowledgement.