Question: Which are the obligatory rak`ats and which are the optional ones in our five prayers?  
    Answer: The five prayers Fajr, Z~uhr, `Asr, Maghrib and `Isha imposed on the Muslims consist of  two, four, four, three and four obligatory rak`ats respectively. These rak`ats called fard rak`ats must be offered in all circumstances.  
    The Prophet (sws) offered some more rak`ats before and after these stipulated ones to set an example in worshipping Allah, and, as such, a believer should try to offer them as much as he can. However, all these rak`ats are optional. Offering them will certainly earn a believer a lot of reward from the Almighty, but not offering them will entail no penalty. These optional rak'ats are:  

    Fajr: two before the fard rak`ats  
    Zuhr: two or four before the fard rak`ats and two after  
    `Asr: two or four before the fard rak`ats  
    Maghrib: two after the fard rak`ats  
    `Isha: two or four before fard rak`ats and two after