A sign ( - a stand-alone hamza) used in the written Arabic language representing a glottal stop. Hamza may appear as a stand-alone letter or most commonly over or under other letters, e.g. (over an alif - ), (under an alif), (over a wÄw - ) or (over a dotless yÄʾ - ). The exact seat of hamza is governed by an orthographic rule - ""seat of hamza rule"".