Computer science is undergoing a fundamental change and is reshaping our understanding of the world. An important aspect of this change is the theory and applications dealing with the gathering and analyzing of large real-world data sets. In this paper, we introduce four research projects in which processing and interpreting large data sets is a central focus. Innovative ways of analyzing such data sets allow us to extract useful information that we would never have obtained from small or synthetic data sets, thus providing us with new insights into the real world.