Arabs were illiterate at the time of the Prophet (SAW). They didn’t know how to read or write.
Many readers won’t find this statement strange at all. Because this is the concept we’re made to digest. And it’s the exact reason for the false belief that Qur’an wasn’t written at the time of the Prophet (SAW). That it was written way after his death. And that leads to doubts or uncertainty in it. But wait! Before developing any ideas, read this first..
Volume 1, Book 3, Number 111:
Abu Juhaifa said, “I asked Ali, ‘Have you got any book (which has been revealed to the Prophet apart from the Qur’an)?’ ‘Ali replied, ‘No, except Allah’s Book or the power of understanding which has been bestowed (by Allah) upon a Muslim or what is (written) in this sheet of paper (with me).’ Abu Juhaifa said, “I asked, ‘What is (written) in this sheet of paper?’ Ali replied, it deals with The Diyya (compensation (blood money) paid by the killer to the relatives of the victim), the ransom for the releasing of the captives from the hands of the enemies, and the law that no Muslim should be killed in Qisas (equality in punishment) for the killing of (a disbeliever).
So, people did actually read and write at that time. And Ali (RA) had a copy of Qur’an written with him. And other books with that…
Conclusion is, not all Arabs were illiterate. A few could read and write. A number of companions had written Qur’anic verses on leather, stones, leaves etc. The Qur’an that we hold in our hands today is the same version that was revealed to the Prophet (SAW). Alhamdulillah. Another thing to thank Allah about! :)