In German orthography, the letter ß, called Eszett (IPA: [ɛsˈtsɛt], S-Z) or scharfes S (IPA: [ˌʃaʁfəs ˈʔɛs], "sharp S"), represents the /s/ phoneme in Standard German when following long vowels and diphthongs. The letter-name Eszett combines the names of the letters of ⟨s⟩ (Es) and ⟨z⟩ (Zett) in German. The character's Unicode names in English are double s, sharp s and eszett. The Eszett letter is currently used only in German, and can be typographically replaced with the double-s digraph ⟨ss⟩ if the ß-character is unavailable. In the 20th century, the ß-character 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.
