Iotation

In Slavic languages, iotified vowels are preceded by a palatal approximant /j/ before a vowel, at the beginning of a word, or between two vowels in the middle of a word, creating a diphthongoid, a partial diphthong.[2] In the Greek alphabet, the consonant is represented by iota (ι). For example, the English apple is cognate to Russian яблоко (jabloko): both come from Proto-Indo-European stem *ābol-. As a result of the phenomenon, no native Slavic root starts with an [e] or an [a] but only with a [je] and [ja]; although other vowels are possible.

As it was invented for the writing of Slavic languages, the original Cyrillic alphabet has relatively complex ways for representing iotation by devoting an entire class of letters to deal with the issue. There are letters which represent iotified vowels; the same letters also palatalize preceding consonants (with or without self-iotation), which is why iotation and palatalization are often mixed up. There are also two special letters (soft sign Ь and hard sign Ъ) that also induce iotation; in addition, Ь palatalizes preceding consonant, allowing combinations of both palatalized (soft) and plain (hard) consonants with [j]. Originally, these letters produced short vowels [i] and [u]. The exact use depends on the language.

The adjective for a phone which undergoes iotation is iotated. The adjective for a letter formed as a ligature of the Early Cyrillic I (І) and another letter, used to represent iotation, is iotified.. The use of an iotified letter does not necessarily denote iotation. Even an iotified letter following a consonant letter is not iotated in most orthographies, but iotified letters imply iotated pronunciation after vowels, soft and hard signs as well as in isolation

In the Cyrillic alphabet, some letter forms are iotified, formed as a ligature of Early Cyrillic I (І) and a vowel.

In old inscriptions, other iotified letters, even consonants, could be found, but they are not in the regular alphabet.

There are more letters that serve the same function, but their glyphs are not made in the same way.

Iotated consonants occur as result of iotation. They are represented in IPA with superscript j after it and in X-SAMPA with apostrophe after it so the pronunciation of iotated n could be represented as [nʲ] or [n'].

When Vuk Karadžić reformed the Serbian language, he created new letters to represent iotated consonants. Macedonian uses two of them, but has its own versions for iotated t and d (resembling the letters Г and К instead of Т and Д):