When you are writing a piece of University work you will almost always need to include sections or ideas from other people’s work. It is important that whoever is reading the work is clear which words or ideas are yours and which came from someone else.
If you do not reference properly, even if you do so by mistake, it will be treated as plagiarism. The University views plagiarism as cheating. Anything which you present as your own which is in fact somebody else’s work is plagiarism.