which is the First printed book in the world?

Gutenberg invented the first workable press that was designed to allow for an easier change of settings between prints. This made it easier to print a book. The book of his choice was the Bible. The Gutenberg Bible is the first printed book. Buying one was an investment, lol. But he printed several and personalized them for the respective buyer. I don't remember how many he originally printed. Not that many. The printing process still took a long time and if you consider how many pages a bible has... I know that there are only still about a handful or so around. And I think three still have all the pages. But don't quote me on that.