The Qur'an is the book of divine guidance and direction for mankind, the text in Arabic is the literal word of Allah revealed to Muhammad over a period of twenty-three years, the Qur'an as God's final revelation to humanity.
The Qur'anic verses were originally memorized by Muhammad's (pbuh) companions as Muhammad (pbuh) recited them, with some being written down by one or more companions.
The Qur'an is exactly the same today as when it was revealed to the prophet Muhammad (pbuh). The simple reason for this is because of the thousands of Muslims who have memorized the entire Qu'ran word for word, and thus, if someone was to attempt to change it, and claim that the edited version was correct, it could easily be proven wrong by these men and women.