Al-Asma' al-Husna
Allah calls His Names the most beautiful and tells us to call on Him by them (7:180). The Prophet ﷺ said: “Allah has ninety-nine Names, one-hundred less one; and he who memorized them all by heart will enter Paradise” (Sahih al-Bukhari 7392). Tap a Name for its own page, with its verses, its tafsir and a du'a.
﴿وَلِلَّهِ ٱلْأَسْمَآءُ ٱلْحُسْنَىٰ فَٱدْعُوهُ بِهَا ۖ وَذَرُوا۟ ٱلَّذِينَ يُلْحِدُونَ فِىٓ أَسْمَـٰٓئِهِۦ ۚ سَيُجْزَوْنَ مَا كَانُوا۟ يَعْمَلُونَ﴾Allah has the Most Beautiful Names. So call upon Him by them, and keep away from those who abuse His Names. They will be punished for what they used to do.
In the well-known order, the order of the list reported by at-Tirmidhi (3507), followed by the other Names explained on IslamFAQ.
Ninety-nine is the number in the hadith (Sahih al-Bukhari 7392), but it is not a limit: al-Sa'di, on 59:24, says His Names are very many, more than anyone but Allah Himself can count or know.
Not a sound one. The hadith of the ninety-nine is in al-Bukhari (7392) and does not list them. The list people pass around, naming each one, comes from at-Tirmidhi (3507), and al-Albani graded it weak.
Al-Bukhari explains the word used in the hadith himself: “To count something means to know it by heart”. Al-Sa'di adds, on 59:24, that Allah loves His Names, loves whoever loves them, and loves His servants to call on Him and ask Him by them.
Because each one points to an attribute of perfection, al-Sa'di says on 7:180. His examples: a knowledge that takes in everything behind Al-Alim, a mercy wide enough for all things behind Ar-Raheem, a power nothing can defeat behind Al-Qadeer.
With the Name that fits the request. Al-Sa'di, on 7:180, gives examples: ask Him for forgiveness and mercy and end with the All-Forgiving, the Most Merciful; ask At-Tawwab to accept your repentance, Ar-Razzaq for provision, Al-Lateef for gentleness. Sulayman did the same when he ended his request with Al-Wahhab (38:35).
قال تعالى: ﴿وَلِلَّهِ ٱلْأَسْمَآءُ ٱلْحُسْنَىٰ فَٱدْعُوهُ بِهَا ۖ وَذَرُوا۟ ٱلَّذِينَ يُلْحِدُونَ فِىٓ أَسْمَـٰٓئِهِۦ ۚ سَيُجْزَوْنَ مَا كَانُوا۟ يَعْمَلُونَ﴾ (الأعراف 7: 180)، قال السعدي: «فيدعى في كل مطلوب بما يناسب ذلك المطلوب، فيقول الداعي مثلا اللّهم اغفر لي وارحمني، إنك أنت الغفور الرحيم، وتب عَلَيَّ يا تواب، وارزقني يا رزاق، والطف بي يا لطيف». وقال في آية الحشر: «له الأسماء الكثيرة جدا، التي لا يحصيها ولا يعلمها أحد إلا الله هو،»، «ومن حسنها أن الله يحبها، ويحب من يحبها، ويحب من عباده أن يدعوه ويسألوه بها.».