X-ray absorption spectroscopy and X-ray emission spectroscopy are complementary to crystallographic methods, particularly for materials science and the study of nanostructure and systems with partial disorder and partial local order, including solutions, gases, liquids, glasses and powders.   This new volume of International Tables for Crystallography has nine parts and over 150 chapters contributed by a wide range of international experts. •Part 1 provides a brief overview and introduction to the background of X-ray absorption spectroscopy (XAS) and experimental facilities. •Part 2 discusses the quantum theory of XAS and related approaches. •Part 3 describes both standard and advanced experimental methods used in XAS, X-ray emission spectroscopy (XES) and related techniques. •Part 4 covers both standard and more advanced pre-processing of data. •Part 5 gives an extensive overview of the analysis of experimental data. •Part 6 provides details of the major software packages for data collection, reduction and analysis. •Part 7 outlines the importance in science, reporting and hypothesis testing of the exchange of input and processed output data, and data deposition. It also presents excerpts of tables of data and supplementary material for XAS, pre-edge studies, X-ray absorption near-edge spectroscopy (XANES) and X-ray absorption fine structure (XAFS) studies. These tables are also available in full as online supporting information. •Part 8 explores a wide range of applications of XAS in fields including materials science, physics, chemistry, biology, earth sciences, catalysis and cultural heritage. •Part 9 presents definitions of the terms and quantities used, as developed by the International Union of Crystallography’s Commission on XAFS.   The volume has been written for the worldwide XAS community of thousands of practitioners, beamline scientists, experts and academics, and for the novice user who wishes to know what XAS and XES can do for them and how they may use these techniques for their particular purposes. The volume is therefore intended to be a self-contained, authoritative reference work that can also be used for training, learning or teaching, providing practical guidance for readers of all levels of experience.   More information on the volumes in the series International Tables for Crystallography can be found at https://it.iucr.org.  X-ray absorption spectroscopy and X-ray emission spectroscopy are complementary to crystallographic methods, particularly for materials science and the study of nanostructure and systems with partial disorder and partial local order, including solutions, gases, liquids, glasses and powders.   This new volume of International Tables for Crystallography has nine parts and over 150 chapters contributed by a wide range of international experts. Part 1 provides a brief overview and introduction to the background of X-ray absorption spectroscopy (XAS) and experimental facilities. Part 2 discusses the quantum theory of XAS and related approaches. Part 3 describes both standard and advanced experimental methods used in XAS, X-ray emission spectroscopy (XES) and related techniques. Part 4 covers both standard and more advanced pre-processing of data. Part 5 gives an extensive overview of the analysis of experimental data. Part 6 provides details of the major software packages for data collection, reduction and analysis. Part 7 outlines the importance in science, reporting and hypothesis testing of the exchange of input and processed output data, and data deposition. It also presents excerpts of tables of data and supplementary material for XAS, pre-edge studies, X-ray absorption near-edge spectroscopy (XANES) and X-ray absorption fine structure (XAFS) studies. These tables are also available in full as online supporting information. Part 8 explores a wide range of applications of XAS in fields including materials science, physics, chemistry, biology, earth sciences, catalysis and cultural heritage. Part 9 presents definitions of the terms and quantities used, as developed by the International Union of Crystallography’s Commission on XAFS. The volume has been written for the worldwide XAS community of thousands of practitioners, beamline scientists, experts and academics, and for the novice user who wishes to know what XAS and XES can do for them and how they may use these techniques for their particular purposes. The volume is therefore intended to be a self-contained, authoritative reference work that can also be used for training, learning or teaching, providing practical guidance for readers of all levels of experience.   More information on the volumes in the series International Tables for Crystallography can be found at https://it.iucr.org.