Sha (Ш, ш) is a letter of the Cyrillic alphabet, representing the consonant sound /ʃ/ or /ʃʲ/. This is equivalent to sh in English, ch in French, sch in German, ş in Turkish, or sz in Polish. In most Latin-alphabet Slavic languages (Czech, Slovak, Slovene, Croatian) this sound is written š, and linguists have adopted this symbol in transliterating ш.

It looks something like a W or more exactly like an E lying on its back. It is the 25th letter of the Russian alphabet.

This sound is described as a voiceless postalveolar fricative and postalveolar fricatives are the major reason why the Glagolitic and later the Cyrillic alphabet were invented because Slavic languages are rich on postalveolar fricatives and you cannot write these sounds with a simple Roman or Greek letter without diacritics. Hence Sha is one of the most typical letters of the Cyrillic alphabet.

Sha has its earliest ties in Hebrew Shin (ש) and when Saint Cyril and Methodius invented Glagolitsa, Sha already possessed its current form and has been the only letter being that permanent in its form. Most letters of Cyrillic script have been derived from Greek and as there was no Greek sign for the Sha sound, Glagolitic Sha was adopted.