In Muslim communities, people are reminded of the salat by the daily calls to prayer, known as adhan. The adhan are delivered from mosques by a muezzin, the mosque's designated caller of prayer. During the call to prayer, the muezzin recites the Takbir and the Kalimah.
Traditionally, the calls were made from the mosque's minaret without amplification, though many modern mosques use loudspeakers so that the faithful can hear the call more clearly. The prayer times themselves are dictated by the position of the sun:
Fajr: This prayer starts off the day with the remembrance of God; it is performed before sunrise.
Dhuhr: After the day's work has begun, one breaks shortly after noon to again remember God and seek His guidance.
'Asr: In the late afternoon, people take a few minutes to remember God and the greater meaning of their lives.
Maghrib: Just after the sun goes down, Muslims remember God again as the day begins to come to a close.
'Isha: Before retiring for the night, Muslims again take the time to remember God's presence, guidance, mercy, and forgiveness.
In ancient times, one merely looked at the sun to determine the various times of day for prayer. In modern days, printed daily prayer schedules precisely pinpoint the beginning of each prayer time. And yes, there are plenty of apps for that.
Missing prayers is considered a serious lapse of faith for devout Muslims. But circumstances do sometimes arise where a prayer time may be missed. Tradition dictates that Muslims should make up their missed prayer as soon as possible or at the very least recite the missed prayer as part of the next regular salat.
Islamic Prayer Time of Different Cities
Fajr Prayer Times Dubai
Dhuhr Prayer Time Dubai