What is the use of movable type printing?

Movable type printing used to be block printing-that is, all the characters on one side to be printed were engraved on a board and then printed. After the appearance of movable type printing in the Northern Song Dynasty in China, it became one of the four great inventions of China to promote the progress of world civilization. Its first function is to save printing cost; Second, it saves printing time; Generally speaking, it makes it possible to popularize knowledge, books are cheaper, and more people can afford books and afford them.