The Introduction should provide readers with the background information needed to understand your study, and the reasons why you conducted your experiments. The Introduction should answer the question: what question/problem did you study?
While writing the background, make sure your citations are:
- Well balanced: If experiments have found conflicting results on a question, have you cited studies with both kinds of results?
- Current: Every field is different, but you should aim to cite references that are not more than 10 years old if possible. Although be sure to cite the first discovery or mention in the literature even if it is older than 10 years.
- Relevant: This is the most important requirement. The studies you cite should be strongly related to your research question.
Once you have provided background material and stated the problem or question for your study, tell the reader the purpose of your study. Usually the reason is to fill a gap in the knowledge or to answer a previously unanswered question. For example, if a drug is known to work well in one population, but has never been tested in a different population, the purpose of a study could be to test the efficacy and safety of the drug in the second population.
The final thing to include at the end of your Introduction is a clear and exact statement of your study aims. You might also explain in a sentence or two how you conducted the study.