What’s that? The terminology of graphic design.

.eps Encapsulated PostScript -graphics, file format
A scaleable vector format that allows resolution independent resizing of vector images. EPS files are created with the Postscript language favored by printers because it enables files to print faster. It combines a postscript description of an illustration with a PICT preview for the screen. This format does not compress files - generally it makes them larger. It is best used to import graphics into professional page layout programs such as InDesign or Quark Xpress or for packaging/delivering press files.