A literature review is a description of the literature relevant to a particular field or topic. It gives an overview of what has been said, who the key writers are, what are the prevailing theories and hypotheses, what questions are being asked, and what methods and methodologies are appropriate and useful. As such, it is not in itself primary research, but rather it reports on other findings.
Here is one definition of a literature review:
"... a literature review uses as its database reports of primary or original scholarship, and does not report new primary scholarship itself. The primary reports used in the literature may be verbal, but in the vast majority of cases reports are written documents. The types of scholarship may be empirical, theoretical, critical/analytic, or methodological in nature. Second a literature review seeks to describe, summarise, evaluate, clarify and/or integrate the content of primary reports."
Cooper, H. M. (1988), "The structure of knowledge synthesis",
Knowledge in Society, Vol. 1, pp. 104-126
A literature review may be purely descriptive, as in an annotated bibliography, or it may provide a critical assessment of the literature in a particular field, stating where the weaknesses and gaps are, contrasting the views of particular authors, or raising questions. Such a review will not just be a summary but will also evaluate and show relationships between different material, so that key themes emerge. Even a descriptive review however should not just list and paraphrase, but should add comment and bring out themes and trends.
A literature review should never be just a list, as in the example below:
"Until recently many researchers have shown interest in the field of coastal erosion and the resulting beach profiles. They have carried out numerous laboratory experiments and field observations to illuminate the darkness of this field. Their findings and suggestions are reviewed here.
JACHOWSKI (1964) developed a model investigation conducted on the interlocking precast concrete block seawall. After a result of a survey of damages caused by the severe storm at the coast of USA, a new and especially shaped concrete block was developed for use in shore protection. This block was designed to be used in a revetment type seawall that would be both durable and economical as well as reduce wave run-up and overtopping, and scour at its base or toe. It was proved that effective shore protection could be designed utilizing these units.
HOM-MA and HORIKAWA (1964) studied waves forces acting on the seawall which was located inside the surf zone. On the basis of the experimental results conducted to measure waves forces against a vertical wall, the authors proposed an empirical formula of wave pressure distribution on a seawall. The computed results obtained by using the above formula were compared well with the field data of wave pressure on a vertical wall.
SELEZOV and ZHELEZNYAK (1965) conducted experiments on scour of sea bottom in front of harbor seawalls, basing on the theoretical investigation of solitary wave interaction with a vertical wall using Boussinesque type equation. It showed that the numerical results were in reasonable agreement with laboratory experimental data."
This example first appeared on the website of the
Language Center, Asian Institute of Technology.
All this extract does is to write a potted summary of the views of three sets of authors; there is no attempt to look at the relationships between the views, or draw out themes.
By contrast, the following extract from a paper quoted in full (see Further information and examples section) does just that:
"In developed countries, a large part of the literature concerned with income-related aspects of disability has tended to focus on the quantitative impact of disability on educational achievement, earnings and income, and on the adequacy and equity of income maintenance schemes and other programmes. The costs and benefits of rehabilitation and vocational employment schemes and employment discrimination have also been recurrent themes. Much of the current popular literature has been to do with removing barriers of all kinds in order to increase the participation of disabled people in the employment market."
It is a paper the main purpose of which is to annotate and/or critique the literature in a particular subject area. It can either be:
A literature review will generally be part of a thesis or dissertation, forming an early context-setting chapter. It may also form a useful background where you are outlining a piece of research, or putting forward a hypothesis.