Prayer is form of worship of God. Prayer has been enjoined on believers five times a day at appointed hours, as given in the Quran in these words:

   “Believers are under the obligation to say their prayers at the appointed hours. (4:103)

These prayers are performed either individually at home or in congregation in mosques. A believer begins his prayer by uttering the words “God is Great”. These words acknowledge that all greatness belongs to God and that the worshipper will lead a life of modesty and humility. Each prayer is segmented into several rak’ahs, or units. In each rak’ah a person stands, bows and prostrates, reciting verses from the Quran and other prayers. These are the five obligatory prayers:

1. Early morning prayer (Fajr): Two rak’ahs between dawn and sunrise

2. Noon prayer (Zuhr): Four rak’ahs, between noon and mid-afternoon 

3. Afternoon prayer (Asr): Four rak’ahs. The time for prayer starts when the length of any object’s shadow reaches a factor (usually 1 or 2) of the length of the object itself plus the length of that object’s shadow at noon. The time for the prayer ends at sunset.

4. Sunset prayer (Maghrib): Three rak’ahs between sunset and early evening

5. Evening prayer (Ishaa): Four rak’ahs from the disappearance of twilight until dawn

During the prayer, a believer refreshes his memory about God’s commandments regarding himself. Then he kneels and prostrates himself before God, in physical expression of the idea that the only course that befits him is to lead his life according to the creation plan of God. The prayer is concluded by turning the face first to the right side, then to the left, and uttering the words Assalamu-alaykum, which means, ‘May the peace and blessings of God be upon you!’ This is a demonstration that spiritually conditioned by prayer, the worshipper is now entering into the world with no other thoughts and feelings in his mind but those of mercy towards others and peace for all mankind.

Source: The Seeker’s Guide