If the term fautographie, photographic error, seems to date back to Man Ray, the practice, in its many forms, is as old as photography itself. Erasures and failures, beautiful or ugly surprises, détournements, slips and mishaps have marked its history, fertilised the avant-gardes, inspired the most important theories and the most fanciful experiments, and sparked aesthetic debates as thorny as they are engaging. This small treatise of photographic “erratology”, for aesthetes, historians of the image and the curious, sets out above all to circumscribe the medium’s slips and to understand what they reveal, staying at a distance from the mere museum of horrors, from collections that line up anomalous specimens. Combining seriousness, precision and lightness with an erudition that draws on the history of images as much as on amateur manuals or the theories of modernity, Clément Chéroux offers a coherent, entertaining and richly illustrated guided tour of this small but inexhaustible gallery of errors.