[1] For most English speakers, the name for the letter is pronounced as /eɪtʃ/ and spelled "aitch"[1] or occasionally "eitch".

The pronunciation /heɪtʃ/ may be a hypercorrection formed by analogy with the names of the other letters of the alphabet, most of which include the sound they represent.

The American Heritage Dictionary of the English Language derives it from French hache from Latin haca or hic.

Anatoly Liberman suggests a conflation of two obsolete orderings of the alphabet, one with H immediately followed by K and the other without any K: reciting the former's ..., H, K, L,... as [...(h)a ka el ...] when reinterpreted for the latter ..., H, L,... would imply a pronunciation of [(h)a ka] for H.[7] The original Semitic letter Heth most likely represented the voiceless pharyngeal fricative (ħ).

While Etruscan and Latin had /h/ as a phoneme, almost all Romance languages lost the sound—Romanian later re-borrowed the /h/ phoneme from its neighbouring Slavic languages, and Spanish developed a secondary /h/ from /f/, before losing it again; various Spanish dialects have developed [h] as an allophone of /s/ or /x/ in most Spanish-speaking countries, and various dialects of Portuguese use it as an allophone of /ʀ/.

It was formerly common for an rather than a to be used as the indefinite article before a word beginning with /h/ in an unstressed syllable, as in "an historian", but the use of a is now more usual.

In 1901, a spelling reform eliminated the silent ⟨h⟩ in nearly all instances of ⟨th⟩ in native German words such as thun ('to do') or Thür ('door').

In Spanish and Portuguese, ⟨h⟩ is a silent letter with no pronunciation, as in hijo [ˈixo] ('son') and húngaro [ˈũɡaɾu] ('Hungarian').

In words where the ⟨h⟩ is derived from a Latin /f/, it is still sometimes pronounced with the value [h] in some regions of Andalusia, Extremadura, Canarias, Cantabria, and the Americas.

Most words that begin with an H muet come from Latin (honneur, homme) or from Greek through Latin (hécatombe), whereas most words beginning with an H aspiré come from Germanic (harpe, hareng) or non-Indo-European languages (harem, hamac, haricot); in some cases, an orthographic ⟨h⟩ was added to disambiguate the [v] and semivowel [ɥ] pronunciations before the introduction of the distinction between the letters ⟨v⟩ and ⟨u⟩: huit (from uit, ultimately from Latin octo), huître (from uistre, ultimately from Greek through Latin ostrea).

Hence, herri ("people") and etorri ("to come") were accepted instead of erri (Biscayan) and ethorri (Souletin).

Specific to the IPA, a hooked ⟨ɦ⟩ is used for a voiced glottal fricative, and a superscript ⟨ʰ⟩ is used to represent aspiration.