The Line printer is a form of high speed impact printer in which a line of type is printed at a time. Printed type is set at fixed positions and a line could consist of any number of character positions but 80 column, 128 column and 160 column variants were common. In a typical design, a fixed font character set is engraved onto the periphery of a number of print wheels, the number matching the number of columns. The wheels spin at high speed and paper and an inked ribbon are stepped past the print position. As the desired character for each column passes the print position a hammer strikes the paper and ribbon causing the desired character to be recorded on the continuous paper. Other variations had the type on moving bars or a spinning chain (e.g. the IBM 1403).

Lineprinters were replaced by continuous Laser printers which no longer had fixed columns or monospaced type and offered a range of fonts as well as graphics. The technology operates in a similar way to single sheet laser printing.

This technology is still in use in a number of applications where high speed impact technology is advantageous, such as where multi-part paper forms are desired. Because of the limited character set engraved on the wheels and the fixed spacing of type, this technology was never useful for material of high readability such as books or newspapers.