diverse types of review studies based on their approach to retrieving and summarizing original findings

background: we are living in an era in which different branches of science are growing very rapidly. therefore, retrieving and summarizing all new valid findings on a specific subject is one of the most important priorities of scientists. the aim of the present article is to categorize different review studies within the health domain based on their approach to retrieving and summarizing original findings.  methods: the most relevant articles have been selected and summarized in order to accomplish the aim of the study.  results: narrative reviews, systematic reviews, meta-analyses from published data, and individual participant data meta-analyses are different types of review studies. more recently, prospectively planned pooled analyses have also been introduced.   conclusions: diverse types of review studies have been developed one by one over the course of time based on their approaches to retrieving and summarizing original findings. therefore, they have their own especial applications and scientists of different disciplines need to know their advantages and disadvantages.