From Instagram and Uber to Alibaba and ChatGPT, platforms shape nearly every aspect of life. They influence the ways we communicate, work, study, shop, vote, and connect. But what exactly are platforms? How do they work and how did they become so powerful?Platforms offers a critical introduction to platforms and platformisation. Written by two leading experts, the book explains how platforms operate as companies, as services, and as technologies or infrastructures. Drawing on real-world examples, Anne Helmond and Fernando van der Vlist unpack key concepts such as platform power, governance, and strategy. They demonstrate that platforms shape economies, cultures, and institutions, and reveal their power to generate value, influence public life, and create new forms of dependence and control. Pedagogical features and practical approaches to analysing platforms are also provided. Accessible, timely, and grounded in global perspectives, this book is a must-read for students and scholars across the social sciences and the humanities, as well as for policymakers and anyone who seeks to understand the role of platforms in our world.