Hamza
The hamza (Arabic: هَمْزَة hamza) (ء) is an Arabic script character that, in the Arabic alphabet, denotes a glottal stop and, in non-Arabic languages, indicates a diphthong, vowel, or other features, depending on the language. Derived from the letter ʿayn (ع), the hamza is written in initial, medial, and final positions as an unlinked letter or placed above or under a carrier character.