Ш, the Russian cursive letter sha
Ш is the twenty-sixth letter of the Russian alphabet and carries a hushing sh sound, more exactly a voiceless retroflex fricative. In cursive it is built from the same element as и, л, м, щ and ы, so certain combinations of these letters cannot be read without broader context.
In words
дедушка · grandfather
бабушка · grandmother
тишина · silence
Easy to confuse with
Looks like w (Latin w)
ш is three down-strokes sitting flat on the baseline. A cursive Latin w is two V shapes and its joins come to points, not to a flat foot.
History
Sha is a letter of the Glagolitic and Cyrillic scripts, and it is used in every variation of the Cyrillic alphabet for Slavic and non-Slavic languages alike. It commonly represents the voiceless postalveolar fricative /ʃ/, like the sh of shoe. More precisely, the sound that ш denotes in Russian is often falsely transcribed as a palatoalveolar fricative, when it is in fact a voiceless retroflex fricative /ʂ/. In English it is romanised as sh, or as š, the equivalent letter in the Latin alphabets of Czech, Slovak, Slovene, Serbo-Croatian, Latvian and Lithuanian.
In handwriting ш is one of several lowercase cursive letters that consist, entirely or in part, of an element identical to the dotless Latin cursive ı, the cursive Greek ι, or half of a cursive u: и, л, м, ш, щ and ы. Certain combinations of them cannot be deciphered unambiguously without knowing the language or having broader context. In волшебник, meaning magician, and домик, meaning little house, the combinations лш and ми are written identically, and лишишь, meaning you will deprive, consists almost entirely of these elements. In some hands the distinction between т and ш also becomes elusive, since both may be written in the shapes of 𝑚 or ɯ.
Russian cursive was developed during the 18th century on the base of skoropis, the 14th to 17th century chancery hand that descended in turn from the earlier Cyrillic bookhands called ustav and poluustav. It became the handwritten counterpart of the so-called civil, or Petrine, printed script of books, and it is what most handwritten Russian in personal letters and schoolwork still uses.