The Fourth revised and enlarged Teaching Edition is based on the Fourth revised and corrected Edition (1996) of Volume A of International Tables for Crystallography, and has its own special subject index. The work comprises the 17 plane groups (two-dimensional space groups), 24 selected space groups and those basic text sections of Volume A which are necessary for the understanding of the space-group examples, for the determination of space groups, and for the transformations between the various space-group descriptions. The new edition contains new diagrams for all plane groups and space groups and includes space group No. 64 (Cmca) as an example of a space group with the `double' glide plane e. The Teaching Edition serves a threefold purpose: it should provide a handy tool for researchers and students to familiarize themselves with the use of the space-group tables in Volume A; it is designed for use in classroom teaching; and it can serve as a laboratory handbook, since the 24 examples chosen include most of the frequently occurring space groups for both organic and inorganic crystals.