When the rule check does not report any problems, then it is time to generate the output file. Most fabricators use a file format called “Gerber”. Essentially, a Gerber file specifies how to draw the traces, pads, rings and other constructs on a PCB layer. In addition to a set of Gerber files, a fabricator also needs a “drill file” to specify the positions and sizes of holes to be drilled.
Different fabricators require different methods to submit the necessary files. Most accept a ZIP file that contains all the individual files with a text file that describes the individual files.