The ancient Christian doxology — praise to the Trinity, used in the Rosary and Liturgy of the Hours.
The Glory Be is the church's briefest, most universal response to the trinitarian God. Where the Apostles' Creed and Nicene Creed describe the Trinity at length, the Glory Be simply praises each of the three Persons by name. It is a prayer of pure adoration without petition.
The closing — "as it was in the beginning, is now, and ever shall be, world without end" — anchors the Trinity in eternity. God's glory does not begin with the prayer; the prayer joins glory that has always existed and will never end. The Greek doxological formula (eis tous aionas ton aionon — "unto the ages of ages") is the source of the "world without end" rendering.
Because the prayer is so brief, it integrates easily into nearly any spiritual practice — making it one of the most-prayed prayers in Christian history. A Catholic praying a full daily Rosary will pray the Glory Be at least five times.