In modern Arabic orthography, hamza may also appear on the line under certain circumstances as though it were a full letter, independent of an alif.

Hamza is derived from the verb hamaza (هَمَزَ) meaning 'to prick, goad, drive' or 'to provide (a letter or word) with hamzah'.

[2] The hamza (ء) on its own is hamzat al-qaṭ‘ (هَمْزَة الْقَطْع, "the hamzah which breaks, ceases or halts", i.e. the broken, cessation, halting"), otherwise referred to as qaṭ‘at (قَطْعَة), that is, a phonemic glottal stop unlike the hamzat al-waṣl (هَمْزَة الوَصْل, "the hamzah which attaches, connects or joins", i.e. the attachment, connection, joining"), a non-phonemic glottal stop produced automatically only if at the beginning of an utterance, otherwise assimilated.

This event occurs in the definite article, or at the beginning of a noun following a preposition, or a verb following a relative pronoun.

The hamza can be written either alone, as if it were a letter, or with a carrier, when it becomes a diacritic: This form has been proposed for the inclusion to the Unicode Standard,[4][5] but the Unicode Script Ad Hoc Group stated that it can be unified with the existing U+0674 ٴ ARABIC LETTER HIGH HAMZA.

This form as well as hamza below alif ⟨إ‎⟩ are both also in Arabic loanwords where the original spelling has been retained.

In the final position hamza is silent or produces a glottal sound, as in Arabic.

In the Uyghur Arabic alphabet, the hamza is not a distinct letter and is not generally used to denote the glottal stop, but rather to indicate vowels.

[10] In the Persian alphabet, the hamza often denotes glottal stop (a similar function to the letter 'ayn ⟨ع⟩), and is commonly found in Arabic loanwords only.

The Kashmiri language written in Arabic script includes the diacritic or "wavy hamza".

In Kashmiri the diacritic is called āmālü mad when used above alif: ٲ to create the vowel /əː/.