pcb includes a stand-alone program (called pcb) which allows users to create, edit, and process layouts for printed circuit boards, as well as a library of footprint definitions for commonly needed elements. While
originally written for the Atari, and later rewritten for Unix-like environments, it has been ported to other operating systems, such as Linux, MacOS/X, and Windows.
While pcb can be used on its own, by adding elements and traces manually, it works best in conjunction with a schematic editor such as gschem from the gEDA project, as gschem will create a netlist, make sure all the elements are correct, etc.
The file in which pcb stores its data ends in .pcb such as myboard.pcb. Additionally, pcb reads individual element footprints from files ending in .fp and netlists from files ending in .net.
There are a couple of different outputs from pcb. If you are having your boards professionally fabricated, you will want to export your board as an RS-247X (aka gerber) file. If you are fabricating your board yourself, you'll probably want to print it. You can also save it as an encapsulated postscript or image file for use in documentation and/or web pages.