QUESTION: What is PostScript?
ANSWER: PostScript is a programming language that's used for describing text and graphics in documents. That is, PostScript is a page-description language.
Files that contain documents described in the PostScript language are normally called "PostScript files"; hence, PostScript is known as a file format as well as a language. Typically, a PostScript filename has a .PS extension, like this:
Most laser printers and imagesetters understand the PostScript language. The Adobe Acrobat Distiller software also understands the PostScript language.
Sometimes a simple example can make things crystal clear, so here is an example of what a PostScript file looks like.
/Helvetica findfont 12 scalefont setfont
72 648 moveto
(This text is 1 inch from the left edge of the page and 9 inches from the bottom.)show
The code in this PostScript file describes a one-page document with one line of text in twelve-point Helvetica type. If you have the Adobe Acrobat software installed on your computer, you can demonstrate for yourself how this PostScript program works. First: highlight the PostScript code, copy it to the clipboard, and paste it into a text editor. Next: save it in ASCII FORMAT (i.e., "plain-text format") under the name PS_FILE.PS. Next, open the PS_FILE.PS file in Adobe Acrobat. Behind the scenes, Adobe Acrobat will convert the PostScript file to PDF format; it will then display the PDF file on the screen. It should look something like this:
This text is 1 inch from the left edge of the page and 9 inches from the bottom.
The Encapsulated PostScript (EPS) file format
There is a special type of PostScript file called an Encapsulated PostScript (EPS) file. EPS is a standard file format for importing and exporting graphics and formatted text among different applications. Click here to learn about EPS files.
See also What is a page-description language?