Printing is the process by which many copies of words and pictures can be reproduced on paper or other materials. Simple wood blocks with carved letters covered with ink were used to print until around 1440, when Johannes Gutenberg developed movable type (a separate piece of metal type for each character). A machine pressed the inked type against paper.
Most modern printing is carried out by offset printing, or lithography. Images are placed on metal printing plates by a photographic process, and a greasy ink is applied that sticks to the areas where the image will be. The inked image is then transferred to a rubber roller and applied onto paper. Some of the fastest newspaper presses can print at a speed of 900 m of paper per minute.
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