|Wikipedia has more information about PostScript.|
PostScript is a printing language to produce scalable text and graphics output to meet professional quality standards. It is possible to embed bitmap grahics within PostScript code. Many usual printing devices use a printing technology that involves rasterizing of any output, no matter if the original graphics is given in a vector format or bitmap format. To output PostScript code a PostScript interpreter is needed (Raster Image Processor, RIP). This PostScript interpreter can be built into the printer itself (Hardware-RIP), or it can be used in form of a software running on a computer separate from the printer (Software-RIP).