What is a screen font and what is a printer font?
Postscript fonts are comprised of two parts: a screen font file and a printer font file. The screen portion of a postscript font is a 72 DPI bitmapped (raster) file which shows a physical representation of what the font will look like when printed. The printer portion of the font file is a mathematically described outline (vector) of the font. Since the printer portion of a font is vector based, it can be scaled to any size by a printer at any resolution. Both parts of a postscript font are needed to send a file to an output device. If one part is missing, the output will either look bitmapped or will default to courier.