This chapter introduces the techniques for subdividing datasets into meaningful subsets and combining datasets for comparative analysis. It emphasizes the importance of subsets for targeted data exploration, highlights strategies for filtering data based on single or multiple conditions and demonstrates how to exclude or combine data using set theory operations such as union, intersection, and difference. The application of base R functions and the “dplyr” package is explored to efficiently manipulate and analyze datasets, preparing readers for more complex data integration and analysis tasks.