Variation Selectors is a Unicode block containing 16 variation selectors used to specify a glyph variant for a preceding character.
They are currently used to specify standardized variation sequences for mathematical symbols, emoji symbols, 'Phags-pa letters, and CJK unified ideographs corresponding to CJK compatibility ideographs.
At present only standardized variation sequences with VS1–VS4, VS7, VS15 and VS16 have been defined; VS15 and VS16 are reserved to request that a character should be displayed as text or as an emoji respectively.
As of Unicode 13.0:[5] This list is continued in the Variation Selectors Supplement.
The following Unicode-related documents record the purpose and process of defining specific characters in the Variation Selectors block: