This Surah is called Al-Fatihah, that is, the Opener of the Book, the Surah with which prayers are begun. It is also called, Umm Al-Kitab (the Mother of the Book), according to the majority of the scholars. In an authentic Hadith recorded by At-Tirmidhi, who graded it Sahih, Abu Hurayrah said that the Messenger of Allah said,
«الْحَمْدُ للهِ رَبَ الْعَالَمِينَ أُمُّ الْقُرْآنِ وَأُمُّ الْكِتَابِ وَالسَّبْعُ الْمَثَانِي وَالْقُرْآنُ الْعَظِيمُ»
(Al-Hamdu lillahi Rabbil-`Alamin is the Mother of the Qur'an, the Mother of the Book, and the seven repeated Ayat of the Glorious Qur'an.)
It is also called Al-Hamd and As-Salah, because the Prophet said that his Lord said,
«قَسَمْتُ الصَّلَاةَ بَيْنِي وَبَيْنَ عَبْدِي نِصْفَيْنِ، فَإِذَا قَالَ الْعَبْدُ:الْحَمْدُدِلله رَبِّ الْعَالَمِينَ، قَالَ اللهُ: حَمِدَنِي عَبْدِي»
(`The prayer (i.e., Al-Fatihah) is divided into two halves between Me and My servants.' When the servant says, `All praise is due to Allah, the Lord of existence,' Allah says, 'My servant has praised Me.')
Al-Fatihah was called the Salah, because reciting it is a condition for the correctness of Salah - the prayer. Al-Fatihah was also called Ash-Shifa' (the Cure).
It is also called Ar-Ruqyah (remedy), since in the Sahih, there is the narration of Abu Sa`id telling the the story of the Companion who used Al-Fatihah as a remedy for the tribal chief who was poisoned. Later, the Messenger of Allah said to a Companion,
«وَمَا يُدْرِيكَ أَنَّهَا رُقْيَةٌ»
(How did you know that it is a Ruqyah)
Al-Fatihah was revealed in Makkah as Ibn `Abbas, Qatadah and Abu Al-`Aliyah stated. Allah said,
﴿وَلَقَدْ ءاتَيْنَـكَ سَبْعًا مِّنَ الْمَثَانِي﴾
(And indeed, We have bestowed upon you the seven Mathani) (seven repeatedly recited verses), (i.e. Surat Al-Fatihah) (15:87). Allah knows best.