A plotter is a printer designed for printing vector graphics. Instead of printing individual dots on the paper, plotters draw continuous lines. This makes plotters ideal for printing architectural blueprints, engineering designs, and other CAD drawings.
There are two main types of plotters – drum and flatbed plotters. Drum plotters (also called roller plotters) spin the paper back and forth on a cylindrical drum while the ink pens move left and right. By combining these two directions, lines can be drawn in any direction. Flatbed plotters have a large horizontal surface on which the paper is placed. A traveling bar draws lines on the paper as it moves across the surface.
Most drum and flatbed plotters provide output sizes that are much larger than standard inkjet and laser printers. For example, a typical inkjet printer creates documents that are 8.5 inches wide. A drum plotter may produce documents that are 44 inches wide. The length of a document printed by a drum plotter is only limited by the size of the paper. Documents printed by flatbed plotters are constrained to the length and width of the printing surface.
NOTE: While pen plotters are still used today, most models have been replaced by wide-format inkjet printers.