Welcome to the 3rd Edition of the Rapra Collection of Infrared Spectra. For this new edition, the collection has been completely revised, and enlarged by the addition of around 200 new spectra. A number of improvements in the layout and design of the book have been made. Some of these, such as a simpler classification system, clearer headings for the spectra, and the insertion of material indexes at the end of each section have been made to make the library quicker and easier to use. It is also the case that, whereas the previous two editions were comprised of four separate libraries covering the transmission and pyrolysate spectra of both rubber and plastic materials, another major improvement for this edition has been the incorporation of an additional, comprehensive library produced using a single bounce attenuated total reflection (ATR) accessory. This is an important development, as since the publication of the second edition of this book in 1997, this type of ATR technique has acquired a high degree of popularity due to its many attributes, including speed and ease of use, the need for only small amounts of sample, and its virtually non-destructive nature.