A printing press is a device for evenly printing ink onto a print medium (substrate) such as paper or cloth. The device applies pressure to a print medium that rests on an inked surface made of moveable type, thereby transferring the ink. Typically used for texts, the invention and spread of the printing press are widely regarded as among the most influential events in the second millennium revolutionizing the way people conceive and describe the world they live in, and ushering in the period of modernity.
The invention of improved movable type mechanical printing is credited to Johannes Gutenberg in 1450 although earlier versions are described in the history of printing. The exact date of Gutenberg's press is debated based on existing screw presses. Gutenberg, a goldsmith by profession, developed a printing system by both adapting existing technologies and making inventions of his own. His newly devised hand mould made possible the rapid creation of metal movable type in large quantities. The printing press displaced earlier methods of printing and led to the first assembly line-style mass production of books. A single Renaissance printing press could produce 3,600 pages per workday, compared to about 2,000 by typographic block-printing and a few by hand-copying. Books of bestselling authors like Luther or Erasmus were sold by the hundreds of thousands in their lifetime.
A rotary printing press is a printing press in which the images to be printed are curved around a cylinder. Printing can be done on large number of substrates, including paper, cardboard, and plastic. Substrates can be sheet feed or unwound on a continuous roll through the press to be printed and further modified if required (e.g. die cut, overprint varnished, embossed). Printing presses that use continuous rolls are sometimes referred to as "web presses". Rotary drum printing was invented by Richard March Hoe in 1843, perfected in 1846, and patented in 1847. (Note – Some sources describe Parisian 'Hippolyte Auguste Marinoni', (1823, 7 January 1904) as the inventor of the Rotary printing press.)
Today, there are three main types of rotary presses; offset including web offset, rotogravure, and flexo (short for flexography). While the three types use cylinders to print, they vary in their method.
Offset lithography uses a chemical process in which an image is chemically applied to a plate (generally through exposure of photosensitive layers on the plate material). Lithography is based on the fact that water and oil do not mix, which enables the planographic process to work. In the context of a printing plate, a wettable surface (the non-image area) may also be termed hydrophilic and (the image area) a non-wettable surface hydrophobic.