Since its early days, crystallography has proven to be a highly interdisciplinary and collaborative science. At the same time, it stands out as a field whose members are strongly committed to education. Crystallographers are well recognized for their dedication to teaching. The determination of the structure of even a simple molecule could become complicated by disorder, twinning, incommensurate modulation, low crystal quality, etc. In addition, analysis of geometrical parameters and intermolecular interactions, graphical representation, structure validation, and manuscript publication often require the help of an expert crystallographer to take the results to publication in a prestigious journal.At the core of IUCr activities is the sponsorship of schools and workshops around the world on different aspects of crystallography, from basic and advanced concepts in symmetry, to structure determination of small and large molecules, powder and singlecrystal diffraction techniques, to new experimental methods, among other topics. Many young crystallographers have benefited from attending prestigious crystallography schools and workshops such as the International School of Crystallography in Erice, the ACA Summer Course on Crystallography, the European Crystallography School, etc. These efforts, strongly supported by the IUCr, aim to compensate for the absence of formal courses in crystallography at the undergraduate and graduate degree levels, as noted by Kantardjieff, Kaysser-Pyzalla, and Spadon in the foreword of the special issue 'Crystallography education and training for the 21st century' in the Journal of Applied Crystallography (Kantardjieff et al., 2010).It is well recognized that the crystallographic community rapidly adapts to new technological advances, in many cases even driving them. This community is also always looking for new approaches and teaching tools, and makes extensive use of online resources, as became evident during the lockdown measures established globally to control the spread of Covid-19. As soon as it was possible, teaching, research, collaboration, meetings, schools, and workshops resumed, using different meeting platforms. Since online teaching requires a great deal of preparation, many crystallographers worked hard to develop online content for students and newcomers to the field, some produced step-by-step guides to the solution of difficult problems, and others dedicated time to contribute to the teaching of fundamental concepts.The special issue (https://journals.iucr.org/special_issues/2023/teaching/index.html) features contributions by B. M. Foxman (Foxman, 2021) and by S.-L. Zheng and M. G. Campbell (Zheng & Campbell, 2021) on teaching space groups. Foxman's approach consists of a tutorial, conceived and written with the late Jerry Jasinski, that presents the crystal classes in five modules of more than 200 PowerPoint 'slides'. Humor (a distinctive trademark of Professor Foxman), historical context, hypothetical dialogues between 'Great Figures of Crystallography', and Q&A combine...
