Two generations after the arrival of the internet and similar technical systems, and one generation after the introduction of the system of protocols that constitute the World Wide Web, we are clearly still struggling to understand the impact of the yet-young digital revolution. As digital technology encourages new modes of thought, speech, and action it also changes the contours of subjectivity along with the horizon of possibility open to political actors, both individually and collectively. In fields such as political theory, political communication, and media studies there remain substantial gaps in our collective understanding of how the internet, and digital technology more broadly, affects political life as such. Understanding Digital Media fills this void by offering a political theory of digital media. F. Vander Valk argues that standard liberal theories of power and political action fail to account for significant aspects of the new media environment; a working political theory of the media must begin by exploring the ways in which media infiltrate, influence, and construct not just political decisions, but the very biological, cognitive, and social information environments in which these decisions are made. In developing this argument, Vander Valk puts forward an approach in which the political subject is theorized as a series of extended social, biological and technological continuities rather than as a discrete and stable entity embedded within a conceptually distinct social context. After introducing the idea of the extended subject, Vander Valk turns to the emerging fields of the philosophy of engineering and software studies to address the question of whether digital technical systems are more akin to language or to action. This extension of political subjectivity traces information flows across several boundaries in order to understand how a particular confluence of information, technology, language, and practice results in an emerging technopolitics. Understanding Digital Media is one of the first books in political theory to address the transformations of subjectivity in the digital age. As essential read which will provide a clear, important and original argument to scholars in the fields of political theory, new media studies, science, technology, and society (STS) programs, and political communication.