The seven ways a pattern repeats along a strip, each with its orbifold name and the translations, mirrors, glides and half-turns that generate it.
Molecular point groups with their operations and character tables, the 230 space groups with a cell builder, and the 17 wallpaper and 7 frieze groups drawn live. The tool needs JavaScript, and WebGL2 for the 3D views; these are the pages it offers: