The number of obligatory (fard) rak'ahs for each of the five daily prayers is fixed and established by the Sunnah of the Prophet Muhammad (peace be upon him).

As explained by Shaykh Ibn Baz and other scholars, the breakdown is as follows:

1. Fajr (Dawn Prayer): Two rak'ahs, in which the Imam recites the Qur'an aloud.
2. Dhuhr (Midday Prayer): Four rak'ahs, which are prayed silently.
3. Asr (Afternoon Prayer): Four rak'ahs, also prayed silently.
4. Maghrib (Sunset Prayer): Three rak'ahs. The first two are prayed with audible recitation by the Imam, and the third is silent.
5. Isha (Night Prayer): Four rak'ahs. The first two are prayed with audible recitation by the Imam, and the final two are silent.

This structure is based on the authentic narrations of how the Prophet (peace be upon him) prayed. Initially, the prayers were prescribed as two rak'ahs each. However, the prayer for a resident was later increased to four for Dhuhr, Asr, and Isha, while the Fajr and Maghrib prayers remained unchanged.

For a traveler, the four-rak'ah prayers (Dhuhr, Asr, Isha) are shortened to two rak'ahs (this is known as qasr). The Fajr and Maghrib prayers are not shortened for the traveler and are prayed with their original number of rak'ahs.

In addition to these obligatory prayers, there are voluntary Sunnah prayers (rawatib) associated with them, such as the two rak'ahs before Fajr and the various Sunnah prayers before or after the other obligatory prayers, which carry great reward but are not obligatory.