Shi'a Islam states that God has 99 known names, and that the 100th name, the greatest name of God, will be revealed by a redeemer figure known as the Mahdi. Baha'is connect the coming of the Bab with the fulfillment of prophecies concerning the Mahdi, and for the Bab, the name of God was Baha, Arabic for "glory."
Many Muslims eschew all depictions of real objects in their artwork, and all forbid visual depictions of God. As such, calligraphy became a major form of decorative artwork. The greatest name is a calligraphic representation of Ya Baha'u'l-Abha, Arabic for "Oh thou the glory of the most glorious."
It is not considered appropriate to use the greatest name as a grave emblem or to be displayed casually.