Printing presses push paper against inked movable type materials to transfer text and images from the type onto the paper. Medieval presses used a handle to turn a wooden screw that moved the platen on which the paper was mounted; the platen squeezed the paper against the type, which was locked in place in a frame, or form. Metal presses, developed late in the 18th century, used steam to drive a cylinder press. Flatbed presses, emerging early in the 19th century, used flat beds to hold the type and either a reciprocating platen or a cylinder to hold paper.