All new research builds on previous research and it is important that authors acknowledge the works on which their research was built, to validate their ideas and arguments, so that the reader can find out more and see how ideas were formed, and as a courtesy to the authors of those works. You therefore need to acknowledge these works by including references to them. Failure to do so can result in plagiarism.
Our guide to Referencing, citations and avoiding plagiarism explains what you need to know to get started with referencing and how to avoid plagiarism and includes a video tutorial as well as links to different types of referencing style.