From open source cultures, piracy, to amateur media and on-demand labour, informal media activities are vibrant in circuits of cultural production, distribution, consumption and labour utilisation in China.　They come in different sizes and shapes, involve multiple actors, often with transnational ties and tensions, and challenge polemic views. Why do these informal activities occur, and how do they evolve? What cultural and social consequences do they have? In what ways do they pose challenges to governance and provoke us to rethink the notion? This book engages with diverse forms of the informal and their equally diverse interactions with the formal in the broader context of the rise of digital platforms, the contingent and complicated state–market interactions, and evolving roles of users. The book provides a vivid and original account of how digital platforms navigate formal and informal boundaries at both operational and discursive levels; how enthusiastic fans, aspiring amateurs, 'ordinary' users and necessity-driven labourers become integral to the formal/informal interface; and how state and non-state actors intervene in governing the formal/informal dynamics. In doing so, the book opens up new insights into the ongoing digital transformation in China.