The nineteenth century saw the beginning and flourishing of the now huge and important field of organophosphorus chemistry. The first compound with a carbon-phosphorus bond was made in 1845, but the scope of this new field did not become apparent until the work of the famous August Wilhelm Hofmann spanning the years 1855-1873. It was only after that, that the field attracted the attention of other chemists. The most notable was August Michaelis who made many valuable contributions. By the end of the century, the field was well established and the way was clear for the dramatic growth in the twentieth century, especially the second half. Phosphorus can be found in various functional groups, and the discovery and description of these, and the development of still useful synthetic methods, are traced in this book.