Swastika

sacred in daily use, and criminal to display

Unicode: U+534D 卍 · U+5350 卐 — encoded as CJK ideographs read wàn, not as a political emblem
Meaning: In South, Southeast and East Asian religious use: auspiciousness, good fortune, the presence of the Buddha or of Vishnu. In one twentieth-century European appropriation: the emblem of the National Socialist party and state.
History: The form is attested for several millennia across cultures with no contact — the Indus Valley, Bronze Age Europe, Greek ornament, Ethiopian design, and the Diné whirling log among others. In China it was made a character: under Wu Zetian it was given the reading wàn, ten thousand or myriad, and it has functioned as an ordinary graph ever since. The NSDAP adopted it in 1920, rotated to stand on a point and set as a black figure on a white disc against red. Its display is now restricted or prohibited in a number of European jurisdictions.
Variants: Orientation, rotation, and setting all vary. The widely repeated rule that arm direction distinguishes the religious symbol from the Nazi one does not hold: both orientations occur in Asian religious use, and the identifying features of the party emblem are the 45° rotation and the white-disc-on-red arrangement, not which way the arms point.
Related: ☭ Ⓐ the other marks whose display is regulated by state; 十 the Cross archetype, on the difficulty of inferring common origin from a form this easy to draw.
Appears: Temples, thresholds, textiles and festival goods across Asia in continuous everyday use; and, in Japanese cartography, as the map symbol for a Buddhist temple. When the Geospatial Information Authority of Japan reviewed its symbols before the 2020 Olympics, it proposed alternatives on foreign-language maps and retained 卍 on domestic ones.
Evolution: A mark independently arrived at many times → a Chinese character for a large number → a continuing religious symbol → an appropriated party emblem → the single sharpest case of one form carrying opposite meanings in two places at the same moment.

Sources · 5

documented The reading wàn assigned to the graph in Tang-period China, and its subsequent life as an ordinary character.
documented The NSDAP’s adoption of the rotated form on a white disc in 1920, and the display restrictions since enacted in several European states.
documented Continuing religious use across Hindu, Buddhist and Jain practice, and the symbol’s status in Japanese cartography, including the Geospatial Information Authority of Japan’s 2016 review of map symbols for foreign visitors.
documented The Unicode Standard, U+534D and U+5350, encoded as CJK unified ideographs.
folk That left-facing is the religious form and right-facing the Nazi one. Extremely widely repeated, including by people trying to be careful, and false — the distinguishing features are rotation and setting.