is the abbreviation for Hewlett Packard Graphics Language.

Originally HPGL commands were only used to drive plotters. However, the fact that virtually every CAD program was able to generate a plot file in this format meant it was an obvious move to interpret these files. This option was particularly interesting in the early days of CAD when manufacturers had few ambitions in terms of high-quality data exchange.

HPGL is a relatively "dumb" format. It naturally follows the logic of a plotter, a logic which is not intended for structuring graphics files. What is more, the possibilities offered by HPGL are generally not utilized by CAD programs, e.g. texts are written as a series of lines instead of using the integrated fonts. For the same reason, the graphics capabilities are restricted to those of the plotter pens. HPGL files can only contain 2D data.

HPGL files are also very large and, after being imported, result in a profusion of polylines or individual elements which can only be reduced to normal proportions again by specific optimization.

A successor has now been defined in the form of HPGL/2 which is able to offer considerably better graphics capabilities.