Subvolume III/22b of the Landolt-Börnstein New Series presents a comprehensive data compilation on defects and impurities in the elemental semiconductors and in the III-V compounds. Data on semiconductor defects were already included in the extended data collection on semiconductors in volumes III/17a...i. Research on semiconductor defects and impurities, however, advanced so rapidly during recent years that a new subvolume on this important topic seemed desirable. The information given in subvolume III/22b ranges from trends on defect properties as predicted by theory and a survey of diagnostic techniques to extensive tables and graphical representations of defect properties. The editor and the authors have endeavoured to find a unified form and to critically select the important and reliable information from the wide range of published data. Discussions of ambiguous results or textbook style explanations are avoided.