Movable type can be broken up and reused: once one book is printed, the same type can set another.
Tips
history
Mostly heard in 活字印刷 or 活字印刷术, movable-type printing, which 毕昇 invented around 1040 with type of fired clay. 活 'living' means the characters can be moved and reset, unlike the carved blocks of woodblock printing, 雕版印刷.