Since the rise of the smartphone, apps have become entrenched in billions of users' daily lives and routines. Apps are used for many purposes, providing powerful ways to care for oneself, connect with others, and more. Accessible across phones and tablets, watches and wearables, connected cars, sensors and cities, they are an inescapable feature of current culture. Gerard Goggin provides a comprehensive and authoritative guide to the development and evolving design of apps as a digital media technology. Covering the technological, social, cultural, and policy dynamics of apps, the issues explored in the book include the economic and business models of apps, privacy and surveillance, controversies, challenges, and regulation. Ultimately, Goggin considers what a post-app world might look like. He argues that apps represent a pivotal moment in the development of digital media, acting as a hinge between the visions and realities of the 'mobile', 'cyber', and 'online' societies envisaged from the late 1980s, and the imaginaries and materialities of the digital societies that emerged from 2010. Apps offer frames, construct tools, and constitute 'small worlds' for users to reorient themselves in digital media settings. This fascinating book will reframe the conversation about the software that underwrites our digital worlds. It is essential reading for students and scholars of media and communication, as well as anyone interested in this ubiquitous modern technology.