August 24, 1456, is believed to be the date on which the first version of the Gutenberg Bible was completed in Mainz, Germany. This claim has no basis in fact. Johannes Gutenberg’s Bible, written in Latin and technically known as the 42-line Bible, carries no date, though at least one copy is known to have been completed sometime in 1455, with large initial letters colored red by hand. The first dated book was Gutenberg’s colorful Mainz psalter (1457). Dated or not, the Gutenberg Bible was the first significant book printed in the West using movable type and the first major book produced on a printing press anywhere in the world. Today, 48 of about 180 of the Bibles are known to exist; only 21 are complete. Gutenberg first used movable-type printing around 1439 in Strasbourg, and he invented a process to mass-produce that metal type. His use of a printing press, similar to agricultural screw presses, and oil-based ink was supremely revolutionary. Most important, he combined the technologies into a coherent system to mass-produce books.