ß

ß (majuscule: ẞ) is a letter of the German alphabet. In German it is called Eszett (pronounced [ɛsˈtsɛt], 'S-Z') or scharfes S ([ˌʃaʁfəs ˈʔɛs], 'sharp S'). It represents the phoneme /s/ in Standard German when following long vowels and diphthongs. In English, it is called double s, eszett, or sharp s. It is currently used only in German, and can be typographically replaced with the double-s digraph ⟨ss⟩ if the character ⟨ß⟩ is unavailable. In the 20th century, ⟨ß⟩ was replaced with ⟨ss⟩ in the spelling of Swiss Standard German (Switzerland and Liechtenstein), while remaining Standard German spelling in other varieties of the German language.

The letter originated as the ⟨sz⟩ digraph used in late medieval and early modern German orthography, represented as a ligature of ⟨ſ⟩ (long s) and ⟨ʒ⟩ (tailed z) in blackletter typefaces, yielding ⟨ſʒ⟩. This developed from an earlier usage of ⟨z⟩ in Old and Middle High German to represent a sibilant that did not sound the same as ⟨s⟩; when the difference between the two sounds was lost in the 13th century, the two symbols came to be combined as ⟨sz⟩ in some situations.

Traditionally, ⟨ß⟩ did not have a capital form, and was capitalized as ⟨SS⟩. Some type designers introduced capitalized variants.