H is the eighth letter in the Latin alphabet. Its name in both British and American English is spelled aitch (pronounced /eɪtʃ/) in most dialects, though in Irish, Australian, Singaporean, South Indian English and very occasionally British English it is haitch /heɪtʃ/. (See the discussion below on the two pronunciations of the name of this letter.) In the International Phonetic Alphabet, this symbol is used to represent two sounds. Its lowercase form, [h], represents the voiceless glottal fricative or 'aspirate', and its small capital form, [ʜ], represents the voiceless epiglottal fricative.
The Semitic letter ח (ḥêṯ) most likely represented the voiceless pharyngeal fricative (IPA: [ħ]). The form of the letter probably stood for a fence or posts. The early Greek H stood for /h/, but later on, this letter, eta (Η, η), became a long vowel, /ɛː/. (In Modern Greek, this phoneme has merged with /i/, similar to the English development where Middle English ea /ɛː/ and ee /eː/ came to be both pronounced as /i:/.)