One who does not have a Muslim training finds it difficult to understand what he or she sees and hears when observing a Muslim at worship alone or with others in a mosque. The eleventh century writer Al-Ghazzali supplies the required information in his Book of the Worship, of which the present work is a translation. The Introduction brings together the acts and utterances which constitute the formal ceremony, which is still practiced today, called 'the Worship', and gives an account of the times when this ceremony is used in the religious life of the Muslim. Annotations attempt to make clear the allusions and the technical terms, the knowledge of which al-Ghazzali takes for granted because he wrote his description of the Worship for Muslims.