In 2001, Mahadev Satyanarayanan (Satya) published the paper, "Pervasive Computing: Vision and Challenges," in IEEE Personal Communications. This was the first paper to substantively explore the implications of Mark Weiser's 1991 vision for a real-world systems infrastructure. It provided the conceptual foundations for what much of the computing industry now calls the Internet of Things (IoT). It also developed a taxonomy showing the deep relationships between distributed systems, mobile computing, and pervasive computing (IoT). This special issue is a retrospective on Satya's vision. The theme articles explore cyber foraging, energy efficiency, privacy concerns, and the emerging field of pervasive data science.