As a recent convert to Islam, I have been a little confused by the issue of Sunnah prayers, I understand that these are extra rak'āt before and after the five daily prayers.

The area that I am unsure about is how many rak'āt each time. I am looking for a definitive list of the Sunnah rak'āt for each prayer, including Jumma prayer, and whether there is any difference between the number if you are at home or in the masjid.

From here, I have the following list:

• Salat al-Fajr - 2 rak‘at before, none after until after sunrise.
• Salat al-Dhuhr - 2 rak‘at before and after
• Salat al-‘Asr - none before or after
• Salat al-Maghrib - 2 after
• Salat al-‘Isha - 2 after

However there is no reference, so I am unable to follow up the information, and also I have found other websites (here and here) stating

• 'Ali (may Allah be pleased with him) reported that the Prophet used to pray four rak'ahs before the 'Asr, ending each two rak'ahs with a tasleem for angels, prophets, and the believers (An-Nawawi, Al-Majmu').

• Ibn 'Umar (may Allah be pleased with him) reported that the Prophet said, "May Allah shower His mercy on the person who prays four rak'ahs before the 'Asr Prayer" (Abu Dawud and At-Tirmidhi).

and

• 1119. 'Ali bin Abu Talib (May Allah be pleased with him)reported: The Prophet (sallallaahu ’alayhi wa sallam) used to perform four Rak'ah before the 'Asr prayer, separating them with Taslim (i.e., offering blessings) on the favourite angels who are near Allah's proximity and the Muslims and the believers who come after them. [At-Tirmidhi].

• 1120. Ibn 'Umar (May Allah be pleased with them) reported: The Prophet (sallallaahu 'alayhi wa sallam) said, "May Allah have mercy on a man who performs four Rak'ah before the 'Asr prayer.'' [Abu Dawud and At-Tirmidhi].

• 1121. 'Ali bin Abu Talib (May Allah be pleased with him) reported: The Prophet (sallallaahu 'alayhi wa sallam) used to perform two Rak'ah before the 'Asr prayer. [Abu Dawud].

Which contradicts what was written in the post that I quoted.