Glottal consonants are consonants using the glottis as their primary articulation. Many phoneticians consider them, or at least the glottal fricative, to be transitional states of the glottis without a point of articulation as other consonants have, while some do not consider them to be consonants at all. However, glottal consonants behave as typical consonants in many languages. For example, in Literary Arabic, most words are formed from a root C-C-C consisting of three consonants, which are inserted into templates such as /CaːCiC/ or /maCCuːC/. The glottal consonants /h/ and /ʔ/ can occupy any of the three root consonant slots, just like "normal" consonants such as /k/ or /n/.
Here are glottal consonants in the International Phonetic Alphabet:
|ɦ||breathy-voiced glottal "fricative"||Czech||Praha||[ˈpra.ɦa]||Prague|
|h||voiceless glottal "fricative"||English||hat||[ˈhæt]||hat|
In many languages, the "fricatives" are not true fricatives. This is a historical usage of the word. They instead represent transitional states of the glottis (phonation) without a specific place of articulation, and may behave as approximants. [h] is a voiceless transition. [ɦ] is a breathy-voiced transition, and could be transcribed as [h̤].
The glottal stop occurs in many languages. Often all vocalic onsets are preceded by a glottal stop, for example in German (in careful pronunciation; often omitted in practice). The Hawaiian language writes the glottal stop as the ‘okina ‘, which resembles a single open quotation mark. Some alphabets use diacritics for the glottal stop, such as hamza ⟨ء⟩ in the Arabic alphabet; in many languages of Mesoamerica, the Latin letter ⟨h⟩ is used for glottal stop, in Maltese, the letter ⟨q⟩ is used, and in many indigenous languages of the Caucasus, the letter commonly referred to as heng ⟨Ꜧ ꜧ⟩ is used.
Because the glottis is necessarily closed for the glottal stop, it cannot be voiced. So-called voiced glottal stops are not full stops, but rather creaky voiced glottal approximants that may be transcribed [ʔ̞]. They occur as the intervocalic allophone of glottal stop in many languages. Gimi contrasts /ʔ/ and /ʔ̞/, corresponding to /k/ and /ɡ/ in related languages.