1) During the Prophet's lifetime, the Quran was preserved through memorization by the Prophet and his companions as well as some early recording on materials like leather and palm leaves.
2) After the Prophet's death, disputes arose around recitation variations, so Caliph Uthman standardized the Quran by compiling an official copy from the Huffaz.
3) Uthman had copies distributed and earlier copies burned to prevent future disputes, establishing the Quran in its final form during his caliphate in the 7th century.