Adhan

The adhān () or the azān () is the Islamic call to prayer. The muezzin reads it out aloud. The root of the word is ' "to permit", and another derivative of this word is ', meaning "ear."
The muezzin reads Adhan in the mosque, sometimes from a minaret. He usually does this five times a day. Adhan is used to call other Muslims to do the prayers. There is a second call, known as iqama (set up) that is used to tell Muslims to line up for the start of the prayers. Sometimes, loudspeakers are used on the minarets. 
Sunni and Shi'a use versions of adhan which are slightly different from each other.