"Referencing is the process of acknowledging other people's work when you have used it in your assignment or research" (Pears and Shields, 2016, p. 1).
It's important to reference a wide range of sources as it will show your teacher the breadth and depth of your research. Referring to the work of other authors and experts helps to build and support your own argument and it allows the reader(s) to refer back to your source material. Referencing links your opinion with the evidence on which it's based and helps you achieve a better mark or grade.
At GSM London we use the Harvard style of referencing apart from Law students who use the OSCOLA style.
Actually there are are many good reasons to take the time to learn how to reference well: