Maghrib prayer

The Maghrib prayer (Arabic: صلاة المغرب‎‎ ṣalāt al-maġrib, '"West [sun] prayer"), prayed just after sunset, is the fourth of five formal daily prayers (salat) performed by practicing Muslims.

The formal daily prayers of Islam comprise different numbers of units, called rak'at.

The Maghrib prayer has three obligatory (fard) rak'at and two recommended sunnah and two non-obligatory nafls. The first two fard rak'ats are prayed aloud by the Imam in congregation, (the person who missed the congregation and is offering prayer alone is not bound to speak the first two rak'ats aloud), and the third is prayed silently.

To be considered valid salat, the formal daily prayers must each be performed within their own prescribed time period. People with a legitimate reason have a longer period during which their prayers will be valid.

Time begins

Time ends

Maghrib prayer in Udaipur, Mughal Empire.

Voluntary prayers accompanying Maghrib in Cairo, Egypt, in 1865.

The redness of the eastern sky - that persists in the east for some time after sunset - disappears from the eastern half of the sky, and thus from above one's head when one looks vertically upwards in the sky.

Time ends

Despite the relatively long period in which valid prayers can be recited, it is considered important to recite the prayer as soon as the time begins.

Shia doctrine permits the midday and afternoon and evening and night prayers to be prayed in succession, i.e. Zuhr can be followed by Asr once the midday prayer has been recited and sufficient time has passed, and Maghrib can be followed by Isha'a once the evening prayer has been recited and sufficient time has passed.

...
Wikipedia