The International Tables Symmetry Database (https://symmdb.iucr.org/), which is part of International Tables for Crystallography, is a collection of individual databases of crystallographic space‐group and point‐group information with associated programs. The programs let the user access and in some cases interactively visualize the data, and some also allow new data to be calculated `on the fly'. Together these databases and programs expand upon and complement the symmetry information provided in International Tables for Crystallography Volume A, Space‐Group Symmetry, and Volume A1, Symmetry Relations between Space Groups. The Symmetry Database allows users to learn about and explore the space and point groups, and facilitates the study of group–subgroup relations between space groups, with applications in determining crystal‐structure relationships, in studying phase transitions and in domain‐structure analysis. The use of the International Tables Symmetry Database in all these areas is demonstrated using several examples. The International Tables Symmetry Database (https://symmdb.iucr.org/), part of International Tables for Crystallography, is a collection of individual databases of crystallographic space‐group and point‐group information. Programs are provided to access and interactively visualize the data, and also allow new data to be calculated `on the fly', facilitating the in‐depth study of group–subgroup relations, domain structures and twinning, families of related crystal structures and phase transitions, and the prediction of new crystal structures.