There's coverage of technical innovations, especially in the early chapters. "Wonderful Things and Faraway Places: the Victorian Explorer", for example, describes the significance of flat-field lenses and the "wet-plate" process, in the context of travel photography in Egypt and elsewhere. Most of the space, however, is devoted to photographers.
Figures like Henri Cartier-Bresson, Robert Mapplethorpe, and Andre Kertesz get treatment by themselves, but most are covered in less detail in spreads on schools, genres, movements, magazines or organisations, and styles: "Photo-essays and Mass Observation", for example, stars August Sander and Bill Brandt. Documentary and art photography are most prominent, but there's coverage of war photography, fashion, the paparazzi, and more. Some of the topics and people are obvious choices, but the inclusion — or omission — of others is likely to be more controversial.
A Crash Course is informative and entertaining, with Yorath's wit and occasional barbs keeping things lighthearted. It is obviously limited in depth, but it is succinct and concise. One obvious improvement would be "further reading" suggestions with each spread: these could have replaced the not particularly useful time-line (of non-photographic events) that appears along the top of each spread, along with cartoon-like drawings.