Acta Crystallographica Section A, Foundations and Advances publishes articles reporting fundamental and mathematical advances in the practice and theory of all areas of structural science in the broadest sense. As well as traditional crystallography, this includes nanocrystals, metacrystals, amorphous materials and quasicrystals. It also covers electron crystallography, diffuse scattering, pair distribution function studies, time-resolved XFEL studies, cryoEM, tomography, small-angle scattering, coherent scattering, diffraction imaging, and the structure of strain and defects in materials. Contributions on advances in analysis tools that are foundational to crystallography, including descriptions and applications of methods, algorithms and software, and the use of emerging computational approaches such as artificial intelligence and machine learning as applied to structural science, are also welcome. Articles are free to publish with no submission fees or page charges. Open access is optional, and it may be covered by a transformative deal with your institution.