Plagiarism is a specific form of academic misconduct. It means using other people’s work without revealing the fact or giving them credit for it. Plagiarism is illegal and a breach of research ethics.
The best way to avoid plagiarism is to ensure that all work and ideas of other people are appropriately acknowledged. UniSA provides an excellent guide to referencing that covers the most common referencing styles used in academic writing, and links to an online module on avoiding plagiarism.
See also Responsible practice in research
Other cases where consideration of intellectual contribution is an issue is when you are researching with other people, including your supervisor, and writing multi-authored works. In general terms, only persons who have made a significant intellectual contribution to the work should be included as authors, and the first author should be the person who wrote the work and contributed most of the intellectual content. It is not appropriate for persons to claim authorship solely because they obtained the funding for the project or provided data. The Australian Code for the Responsible Conduct of Research (PDF 508kb, download Adobe Acrobat) recommends in Section 5.4 that all co-researchers (which includes you as a research student) should consider who will be included as authors, and in what order, at a very early stage of preparing the written work.
Information on Intellectual Property