As the name suggests, a literature review is an overview of the published academic articles, books and book chapters on matters relevant to your PhD. The review may also include articles published in professional journals and newspapers, as well as Government reports and any other relevant information. It should combine a descriptive and critical approach that is focused on your research question and should be sufficiently comprehensive. It should include all of the major publications, but it does not need to include everything that has ever been published on the topic. In other words, writing the literature review requires you to selectively use prior research on the topic so that every cited publication adds something useful to the review.
The reasons for completing a literature review are:
One way of presenting the literature review is as a separate chapter within your PhD. This approach works very well for those PhDs involving a significant empirical element, which is likely to be the case for doctorates in science or social science disciplines. For disciplines, such as law or philosophy, where the research is more normative instead of empirical, it may be better to incorporate the literature review more diffusely throughout the thesis. The PhD Consultancy can help you with these issues and all aspects of writing a high quality literature review.