Data science, as a foundation for knowledge discovery and augmentation in the digital age, is itself built upon fundamental research from many contributing disciplines. Milestones and Millstones publishes foundational achievements, theoretical breakthroughs, and methodological marvels pertaining to data science, ranging from ethical conundrums to quantum computing and everything in-between. It aims to push the frontiers of research on some of the most perplexing problems, to generate new directions of inquiry, and to motivate inquisitive minds worldwide to challenge themselves to tackle provocations put forward by data science.