"He (God) has sent down to you the Book (the Qur'an) with truth, confirming what was revealed before; And He sent down the Torah (of Moses) and the Gospel (of Jesus) before this as a guide in humankind; and He sent down the Criterion (the Qur'an)." (Qur'an 3:3-4)
The Qur'an was memorized by Prophet Muhammad and his followers, dictated to his companions, and written down by scribes, who cross-checked it during the Prophet's lifetime. Not one word of its 114 surahs (chapters) has been changed over the centuries. The Qur'an is in every detail the same unique and miraculous text that was revealed to Muhammad over fourteen centuries ago.
The Qur'an is the principle source of every Muslim's faith and practice. It deals with all subjects that concern us as human beings, including wisdom, doctrine, worship and law; but its basic theme is the relationship between God and His creatures. At the same time, the Qur'an provides guidelines for a just society, proper human conduct and equitable economic principles.
Holy Quran Online: http://quran.al-islam.org/
English/Arabic Holy Quran: http://www.quranexplorer.com/quran/
eBook of Holy Quran: http://www.quranonline.net/ebooks.htm
Audio of the Holy Quran: http://quranicaudio.com/