Reviewing previous studies when writing a literature review is essential because it helps establish the foundation of your research by highlighting existing knowledge, theories, and methodologies in your field. It allows you to identify gaps, avoid duplicating previous work, and refine your research question. By understanding the context of past research, you can build on established findings, select appropriate methods, and position your study to contribute something new. Additionally, a well-rounded review demonstrates your understanding of the field, enhances the credibility of your work, and ensures that your research is original and relevant to ongoing academic discussions.