In this book, Brian Lennon demonstrates the power of a philological approach to the history of programming languages and their usage cultures. In chapters focused on specific programming languages such as SNOBOL and JavaScript, as well as on code comments, metasyntactic variables, the very early history of programming, and the concept of DevOps, Lennon emphasizes the histories of programming languages in their individual specificities over their abstract formal or structural characteristics, viewing them as carriers and sometimes shapers of specific cultural histories. The book's philological approach to programming languages presents a natural, sensible, and rigorous way for researchers trained in the humanities to perform research on computing in a way that draws on their own expertise. Combining programming knowledge with a humanistic analysis of the social and historical dimensions of computing, Lennon offers researchers in literary studies, STS, media and digital studies, and technical fields the first technically rigorous approach to studying programming languages from a humanities-based perspective.