Soft sign

Slavic letters
А Б В Г Ґ Д Ђ Ѓ Е Ѐ Ё Є Ж З Ѕ И Ѝ І Ї Й Ј К Л Љ М Н Њ О П Р С Т Ћ Ќ У Ў Ф Х Ц Ч Џ Ш Щ Ъ Ы Ь Э Ю Я
Non-Slavic letters
Ӑ А̄ А̊ А̃ Ӓ Ӓ̄ Ә Ә́ Ә̃ Ӛ Ӕ Ғ Г̧ Г̑ Г̄ Ҕ Ӻ Ӷ Ԁ Ԃ Ꚃ Ꚁ Ꚉ Ԫ Ԭ С́ Ӗ Е̄ Е̃ Ё̄ Є̈ Ӂ Җ Ꚅ Ӝ Ԅ Ҙ Ӟ З́ Ԑ Ԑ̈ Ӡ Ԇ Ӣ И̃ Ҋ Ӥ Қ Ӄ Ҡ Ҟ Ҝ Ԟ Ԛ Ӆ Ԯ Ԓ Ԡ Ԉ Ԕ Ӎ Ӊ Ң Ԩ Ӈ Ҥ Ԣ Ԋ О̆ О̃ О̄ Ӧ Ө Ө̄ Ӫ Ҩ Ԥ Ҧ Р̌ Ҏ Ԗ Ҫ Ԍ Ꚑ Ҭ Ꚋ Ꚍ Ԏ У̃ Ӯ Ӱ Ӱ́ Ӳ Ү Ү́ Ұ Х̑ Ҳ Ӽ Ӿ Һ Һ̈ Ԧ Ꚕ Ҵ Ꚏ Ҷ Ӵ Ӌ Ҹ Ꚓ Ꚗ Ꚇ Ҽ Ҿ Ы̆ Ы̄ Ӹ Ҍ Э̆ Э̄ Э̇ Ӭ Ӭ́ Ӭ̄ Ю̆ Ю̈ Ю̈́ Ю̄ Я̆ Я̄ Я̈ Ԙ Ԝ Ӏ
Archaic letters
Ꙁ Ꙃ Ꙅ Ꙇ Ꙉ Ҁ Ѻ ОУ Ꙋ Ѡ Ѽ Ꙍ Ѿ Ꙏ Ѣ Ꙑ Ꙓ Ꙕ Ꙗ Ѥ Ѧ Ꙙ Ѫ Ꙛ Ѩ Ꙝ Ѭ Ѯ Ѱ Ѳ Ѵ Ѷ Ꙟ Ꙡ Ꙣ Ꙥ Ꙧ Ꙩ Ꙫ Ꙭ ꙮ Ꚙ Ꚛ
List of Cyrillic letters Cyrillic digraphs

The soft sign (Ь, ь, italics Ь, ь; Russian: мягкий знак Russian pronunciation: [ˈmʲæxʲkʲɪj znak]) also known as the front yer or front er, is a letter of the Cyrillic script. In Old Church Slavonic, it represented a short (or "reduced") front vowel. As with its companion, the back yer ⟨ъ⟩, the vowel phoneme that it designated was later partly dropped and partly merged with other vowels.

In the modern Slavic Cyrillic writing systems (all East Slavic languages and Bulgarian and Church Slavic), it does not represent an individual sound but indicates palatalization of the preceding consonant.

It was also used in the Soviet Union in the Latinized Karelian alphabet, made official in 1931 and used until re-Cyrillicization of Karelian in 1937.

The soft sign is normally written after a consonant and indicates its softening (palatalization). Less commonly, the soft sign just has a grammatically determined usage with no phonetic meaning (like Russian: туш 'flourish after a toast' and тушь 'India ink', both pronounced [tuʂ] but different in grammatical gender and declension). In East Slavic languages and some other Slavic languages (such as Bulgarian), there are some consonants that do not have phonetically different palatalized forms but corresponding letters still admit the affixing soft sign.

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Wikipedia