The Quran was completely revealed and recorded in the life of Holy Prophet (peace be upon him). During the last hajj in the prophet's life, the following verse was revealed:
This day have I perfected your religion for you, completed My favour upon you, and have chosen for you Islam as your religion. (Chapter 5 Al-Maeda:3)
The way that Quran was primarily preserved was through the memories of prophet (peace be upon him) and later through his companions. The word "Quran" has originated from 'Qira' that means "recite". Thousands of Prophet's companion memorized the Quran by heart in his life time and use to revise those verse every passing day of their lives. The Quran was also preserved in written form on various mediums but was not compiled in the form of a book during the life time of prophet (peace be upon him). After prophet passed away and many people started claiming the false prophet hood, the first Caliph of Islam Abu Bakr(RA) sent out forces on various fronts to tackle them. In one of the fronts in Yammama, many muslims Huffaz(people who memorized Quran by heart) died and as a result an emergency meeting was called upon by the Caliph comprising of all top companions of Prophet(peace be upon him) to discuss the most effective methods of saveguarding Quran. They all agreed that the Quran has to be written in a form of a book to be preserved and propagated. The first official copy of Quran was written within a couple of years of Prophet's(peace be upon him) death and during the 2 years era of Abu Bakr(RA) caliphate. Many copies were made of that official copy and were also kept in the houses of Aisha(RA) and Hufza (RA). During the time of Caliph Uthman(RA), the Islam spread to a much wider boundaries than Arabia and people started to recite the Quran based on their local dialect. Uthman(RA) after consulting with other companions of prophet(peace be upon him) made an effort to join all muslims on one dialect of Hijaz in which Quran was originally revealed and sent the official copies to the capitals of different states. He asked people to voluntarily destroy their existing copy and instead use the official copy to keep the text uniform. There were still 100 of 1000s of huffaz among muslims including many companions of Prophet(peace be upon him) and they all verified and attested those official copies before they were made public.
We have, without doubt, sent down the Message; and We will assuredly guard it (from corruption). (Al-Hijr:9)
No wonder that the Quran is preserved upto the letter in every home of muslims around the world. There is not even a minor difference between the earliest manuscript of Quran and between the ones that we found in the present time. There is not a single book in the history, including Bible, that could claim the same. Indeed, that act of preservation of divine word itself is the greatest of miracles.
