Who wrote the Qur’an and how was it put together?.

Firstly:

 Allaah has guaranteed to preserve this Qur’aan Himself. Allaah says (interpretation of the meaning):

 “Verily, We, it is We Who have sent down the Dhikr (i.e. the Qur’aan) and surely, We will guard it (from corruption)”
 [al-Hijr 15:9]

 Secondly:

 Literacy was not widespread among the Arabs. Allaah described them in such terms when He said (interpretation of the meaning):

 “He it is Who sent among the unlettered ones a Messenger (Muhammad) from among themselves”
 [al-Jumu’ah 63:2]

 They used to memorize the Qur’aan by heart, and a few of them used to write down some verses or soorahs on animal skins, thin white stones and the like.

 Thirdly:

 At first the Prophet (peace and blessings of Allaah be upon him) forbade the writing of anything other than the Qur'aan, and he forbade them to write down his words for a while, so that the Sahaabah would focus on memorizing the Qur' aan and writing it down, and so that the words of the Prophet (peace and blessings of Allaah be upon him) would not be confused with the words of Allaah, and so the Qur'aan was protected from anything being added or taken away.

 Fourthly:

 The Prophet (peace and blessings of Allaah be upon him) appointed a group of his companions who were trustworthy and knowledgeable to write down the revelation. They are known in their biographies as those who wrote down the Revelation, such as the four Caliphs, 'Abd-Allaah ibn 'Amr ibn al-'Aas, Mu'aawiyah ibn Abi Sufyaan, Zayd ibn Thaabit and others – may Allaah be pleased with them all.

Fifthly: 

The Qur’aan was revealed in seven dialects as was narrated in the saheeh hadeeth of ‘Umar ibn al-Khattaab (may Allaah be pleased with him) from the Prophet (peace and blessings of Allaah be upon him). This was narrated by al-Bukhaari (2287) and Muslim (818); these were the dialects of the Arabs which were known for their eloquence. 

Sixthly: 

The Qur’aan continued to be preserved in the hearts of the Sahaabah who had memorized it, and on the skins and other materials until the time of the caliph Abu Bakr al-Siddeeq (may Allaah be pleased with him).
he consulted the senior Sahaabah about compiling the Qur’aan in a single book so that it would remain preserved and would not be lost. He entrusted this mission to the chief of memorizers Zayd ibn Thaabit

Then the complete manuscript (copy) of the Qur’aan remained with Abu Bakr until he died, then with 'Umar until the end of his life, and then with Hafsah, the daughter of 'Umar (may Allaah be pleased with him).

 The Sahaabi Zayd ibn Thaabit (may Allaah be pleased with him) knew the Qur’aan by heart but he was methodical in his confirmation; he would not agree to write down any verse until two of the Sahaabah testified that they had heard it from the Messenger of Allaah (peace and blessings of Allaah be upon him).

 This Mus-haf (written copy of the Qur’aan) remained in the hands of the caliphs until the time of the Rightly-Guided Caliph ‘Uthmaan ibn ‘Affaan (may Allaah be pleased with him).

The Sahaabah (may Allaah be pleased with them) had dispersed to different lands, and they used to recite the Qur'aan according to what they had heard of the seven recitations from the Messenger of Allaah (peace and blessings of Allaah be upon him) , and each of their students used to recite according to what he had heard from his shaykh.

So they thought that they should unite the people in following one recitation, which was in the dialect of Quraysh in which the Qur’aan had first been revealed, so as to dispel any disputes and resolve the matter. ‘Uthmaan (may Allaah be pleased with him) was consulted, and he agreed with this opinion.

Hafsah sent it to 'Uthmaan. Then 'Uthmaan ordered Zayd ibn Thaabit, 'Abdullah ibn al-Zubayr, Sa’eed ibn al-‘Aas and ‘Abd al-Rahmaan ibn Haarith ibn Hishaam to copy out the manuscripts. 'Uthmaan said to the three men who were from Quraysh (the tribe of which the Prophet (peace and blessings of Allaah be upon him) was a member)

, [28.10.20 10:31]
, “In case you disagree with Zayd ibn Thaabit on any point in the Qur'aan , then write it in the dialect of Quraysh, for the Qur'aan was revealed in their tongue." They did so, and when they had written many copies, 'Uthmaan returned the original manuscripts to Hafsah.

 'Uthmaan sent to every Muslim province one copy of what they had copied

The Qur’aan has remained and will remain narrated from generation to generation and preserved in men's hearts until the Day of Resurrection. This is how Allaah has preserved His Book, in confirmation of the verse in which He says (interpretation of the meaning):

 “Verily, We, it is We Who have sent down the Dhikr (i.e. the Qur’aan) and surely, We will guard it (from corruption)”

 [al-Hijr 15:9]

And Allaah knows best.
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