Isotype (International System of Typographic Picture Education) is a system of pictograms designed to communicate complex information in a nonverbal way. Developed in 1936 by a team of sociologists lead by Otto and Marie Neurath, this process of 'transforming' data into visual form has strongly influenced the fields of graphic design. The Principles of Making Isotype Charts is the first English-language primer on Isotype the foundation of the modern-day pictographic signals found in airports, train stations, highway signs, and computer interfaces. Featuring illustrated examples and essays, including a previously unpublished essay by Marie Neurath, The Transformer is a long-overdue appreciation of an important moment in the history of visual communication.