We take the printed book for granted. And yet before the late fifteenth century, every book (or scroll) had to be copied by hand, which meant that every one was slightly different--and expensive!
Think about trying to copy even one page by hand without making errors. Now think about copying a book as long as the Bible. Medieval scribes really wanted to be accurate and were constantly checking for slips, but in practice errors were inevitable. Even if the text of two manuscript books were identical, the page breaks and line breaks would vary.
If someone had written a chronicle or treatise of which he (or she) was particularly proud, s/he would loan it to others, who would then copy it. Two twelfth-century monasteries located near Dijon, St.-Bénigne and Bèze, shared a chronicle, written originally at St.-Bénigne (with a lot about the wonders of that monastery), but which the copier at Bèze modified to make his monastery look more interesting.
Johannes Gutenberg developed the first printing press, producing several Bibles, his most famous production, in the 1450s. It had long been possible to carve a piece of wood, ink it, and press it onto paper (they had paper by the fifteenth century), but it took an awfully long time to carve a piece of wood, working backwards, and it really didn't work for text.
Gutenberg's big contribution was movable type. Rather than trying to carve a whole page, one just had to make a whole lot of individual letters. Then, one assembled a page out of the letters, inked them, and pressed them onto paper, making as many copies as one wanted. (It's called a "press," by the way, because one pressed the inked letters very hard onto the paper, using a screw mechanism, to make sure the ink transferred.)
Once a page was set up and locked into place, one could make as many pages as one wanted very quickly, certainly far more quickly than copying by hand, and each one was identical. When one was through with the page, the letters could be tossed back into their boxes for the next time. The metal used for the letters was very high quality, having been developed as part of the advances in metallurgy needed as gunpowder became more common (one did not want a cannon that would blow up).
The price of books immediately dropped, putting them in a price range far more people could afford. Indeed, it has been argued that the rapid spread of revolutionary ideas during the Protestant Reformation of the sixteenth century was only made possible by the printing press, which was able to produce pamphlets, broadsheets, and the like. (For more on medieval books before the printing press, click here.)
Gutenberg's style of printing persisted until the nineteenth century, then was replaced by industrial printers and linotype. More recently, typesetting has all been done by computers, and a lot of books are actually ebooks, rather than physical books.
But a lot of people, including me, still prefer a printed book, which is why I have had "The Starlight Raven" printed. It can be ordered directly from the publisher, CreateSpace, by clicking here, and is also available on Barnes & Noble and Amazon; you get a discount from Amazon if you buy both the ebook and printed versions together. It can also be ordered through any bookstore.
And check out this interview!