How many compulsory prayers must a Muslim observe daily?

A Muslim must observe five compulsory (fard) prayers every day. These five daily prayers are the second pillar of Islam and were prescribed during the Prophet's night journey (Isra and Mi'raj). They are:

1. Fajr - the dawn prayer, performed before sunrise (2 units/rak'at)
2. Dhuhr - the midday prayer, performed after the sun passes its zenith (4 rak'at)
3. Asr - the afternoon prayer, performed in the late afternoon (4 rak'at)
4. Maghrib - the sunset prayer, performed just after sunset (3 rak'at)
5. Isha - the night prayer, performed after twilight has disappeared (4 rak'at)

Together these five prayers total 17 obligatory rak'at per day. The Qur'an commands the establishment of prayer in numerous verses, and the Prophet (peace be upon him) said in an authentic hadith that the five daily prayers are like a river at one's door in which one bathes five times a day, washing away sins.