The muezzin (مُؤَذِّن) is the person who proclaims the call to the daily prayer (ṣalāt) five times a day (Fajr prayer, Zuhr prayer, Asr prayer, Maghrib prayer and Isha prayer) at a mosque. The muezzin plays an important role in ensuring an accurate prayer schedule for the Muslim community. The English word muezzin is borrowed from مُؤَذِّن, mu.ʔað.ðin, simplified mu'azzin, the active participle of أَذَّنَ "to call". Thus, it means "the calling one". The professional muezzin is chosen for his good character, voice and skills to serve at the mosque. Muezzins are typically men. The muezzin is not considered a cleric, but in a position comparable to a Christian verger. He is responsible for keeping the mosque clean, for rolling the carpets, for cleaning the toilets and the place where people wash their hands, face and feet when they perform the Wuḍu' (Arabic: wuḍū’ وُضُوء, the "purification" of ablution) before offering the prayer. When calling to prayer, the muezzin faces the qiblah, the direction of the Ka'bah in Makkah, while reciting the adhan. From the fourteenth century, initially in Mamluk Egypt but then spread into other parts of the Islamic world, major mosques might employ a related officer, the muwaqqit, who determined the prayer times using mathematical astronomy. Unlike the muezzin who were typically chosen for their piety and beautiful voice, the qualification of the muwaqqit required special knowledge in astronomy. Historian Sonja Brentjes speculates that the muwaqqit might have evolved from a specialised muezzin, and that there might not have been a clear delineation between the two offices. Some celebrated muwaqqits, including Shams al-Din al-Khalili and ibn al-Shatir, were known to have once been muezzins, and many individuals held both offices simultaneously. Today, with the production of electronic devices and authoritative timetables, a muezzin in a mosque can broadcast the call to prayer by consulting a table or a clock without requiring the specialised skill of a muwaqqit.