Yer

A yer is one of two letters in Cyrillic alphabets, namely ъ (ѥръ, jerŭ) and ь (ѥрь, jerĭ). The Glagolitic alphabet used as their respective counterparts the letters and . They originally represented phonemically the "ultra-short" vowels in Slavic languages (including Old Church Slavonic), collectively known as the yers. In all Slavic languages they either evolved into various "full" vowels or disappeared, in some cases leaving palatalization of adjacent consonants. At present, the only Slavic language that uses "ъ" as a vowel sign (pronounced /ɤ/) is Bulgarian (although in many cases it corresponds to earlier "ѫ", originally pronounced /õ/). Many languages using the Cyrillic alphabet have kept one or more of the yers to serve specific orthographic functions.

The back yer (Ъ, ъ, italics Ъ, ъ) of the Cyrillic script, also spelled jer or er, is known as the hard sign in the modern Russian and Rusyn alphabets and as er golyam (ер голям, "big er") in the Bulgarian alphabet. Pre-reform Russian orthography and texts in Old Russian and in Old Church Slavonic called the letter "back yer". Originally this yer denoted an ultra-short or reduced middle rounded vowel.