This volume reflects the discussion that emerged around the controversial concepts "communication form", "communicative practice", "medium" and "genre". It provides a comprehensive overview of the history and current state-of-affairs of these concepts, and combines theoretical contributions from various perspectives with thorough empirical studies of current communication forms, media, and practices. The contributions deal with fields ranging from public signage in cities, video games and self-tracking to historical accounts of changing communicative potentials and practices concerning the "National Geographic Magazine" and the personal blog. Due to its interdisciplinary character, the volume points out various new directions for future research.