When you are selecting literature, it is important to think carefully about what you want to include and what you do not want to include. We call this inclusion and exclusion criteria.

Inclusion criteria describe which elements are included in your study
Exclusion criteria describe which elements are excluded from your study

Inclusion and exclusion criteria help you to limit your study and to find the research that is most relevant for your research question. These can be things that are not mentioned in your research question, but which affect your choice of literature—for instance, what kind of literature you wish to use, which language the literature should be written in, the age of participants in the study, geographic area, or range of publication dates for the articles.

In some cases, you will need to specify parts of your research question with the help of inclusion and exclusion criteria. For example, if you wish to study young adults as a group, you may need to specify who counts as a young adult, for instance people between the ages of 16-29. That is an inclusion criterion.

Remember:

Inclusion and exclusion criteria should be clear, concise, and relevant to your research question.
Using inclusion and exclusion criteria can help you to limit your study and focus on the most relevant data.
Ensure that you can justify your choice of inclusion and exclusion criteria.