Moveable type is type in which each individual character is cast on a separate piece of metal. It replaced woodblock printing, allowing the arrangement of individual letters and other characters on a page, rather than requiring the carving of entire pages at a time.
It may have first been invented in Korea in the thirteenth century. Movable type is an important component of the Printing Press.
Sources
The Earth and Its Peoples A Global History, Bulliet et al., 2005.