PostScript (PS) is a page description language and programming language used primarily in the electronic and desktop publishing areas.
PostScript broke with tradition by combining the best features of both printers and plotters. Like plotters, PostScript offered high quality line art and a single control language that could be used on any brand of printer. Like dot-matrix printers, PostScript offered simple ways to generate pages of text and raster graphics. Unlike either, PostScript could place all of these types of media on a single page, which offered far more flexibility than any printer or plotter previously had.
PostScript went beyond the typical printer control language and was a complete programming language of its own. Many applications can transform a document into a PostScript program whose execution will result in the original document. This program can be sent to an interpreter in a printer, which results in a printed document, or to one inside another application, which will display the document on-screen. Since the document-program is the same regardless of its destination, it is called device-independent.
PostScript is also noteworthy for implementing on-the fly rasterization; everything, even text, is specified in terms of straight lines and cubic Bézier curves (previously found only in CAD applications), which allows arbitrary scaling, rotating and other transformations. When the PostScript program is interpreted, the interpreter converts these instructions into the dots needed to form the output. For this reason PostScript interpreters are also sometimes called PostScript Raster Image Processors, or RIPs.