According to Muslim tradition, the Holy Quran is the word of God and has no authorship. According to the tradition, God revealed the writings of the Quran to the prophet Mohammad over a period of 23 years.
Following Mohammad's death in 632 CE, the first caliph Abu Bakr wanted to collect the teachings into book form. He tasked Zayd ibn Thabit with collecting the verses from palm leafs, oral testimonies from Mohammad's followers and parchments. The process took a period of 20 years.
Many scholars believe, however, that the scattered writings of the Quran existed during Mohammad's lifetime, and that by the time of his death, many of his followers had committed it to memory.