History of Printing
For four thousand years after the invention of writing in Iraq, all writing was done by hand, a character at a time. When people needed a copy of a book, they had to pay a scribe to copy it out for them by hand. Of course this made books very expensive, and only the richest people could have them.
Wong Jei's block-printed scroll, 868 AD
Then a faster method was invented: printing. Somebody in Tang Dynasty China, about 650 AD, had the idea of carving wooden blocks with a page of text, then inking it and pressing paper on the block to print a page. The oldest printed scroll we know of - some Buddhist sayings - comes from north-west China, and it was printed about 700 AD. Uighur printers used this method for their Manichaean texts in the later 700s.
The scroll shown here, which was printed in 868 AD, is also a Buddhist holy text, like the Bible is for Christians. People in China who were Buddhists believed that copying out these texts would bring you merit, like good luck. This scroll was printed by a man called Wong Jei, for his parents. The government had killed thousands of Buddhists in the 840s and 850s, and destroyed thousands of Buddhist texts, so it must have seemed very important to create many copies of these texts.
Chinese moveable type
Wong Jei's scroll was block printed - the whole page carved together - but by the 1000s AD an alchemist named Pi Sheng in China had invented the more flexible system of moveable type - carving each Chinese character separately on small fired clay blocks and arranging them to make words, so that the same blocks could be re-used to make many different texts.
About five hundred years later, people all across Europe and Asia began to use moveable type made out of metal, which worked better than the old clay type. In Europe, in the 1400s AD, Gutenberg used moveable metal type made from a mixture of lead, tin, and antimony to print a Christian Bible. Probably printers in Europe had seen Chinese block printing through trade across West Asia, but they seem to have come up with the idea of moveable type on their own. They had, however, learned about rag paper from China (through the Islamic Empire) - you couldn't print onto parchment or papyrus, so they couldn't invent printing until they learned about paper.
Here's a video of a man making a 17-color woodblock print