The Gerber format is a computer file format which is used by makers of printed circuit board (PCB) software. Information contained in a Gerber format file describes the printed circuit board to which it is associated, providing the computer with its parameters, including its solder, legend, and description. This information is like the blueprint of the printed circuit board, allowing the computer and software designers to know how and where to access the various sections of the board. Of the two general types — RS-274-D and RS-274-X — only the RS-274-X format is currently used.
Files with this format contain commands and coordinate data which allow the computer, and individuals programming for the computer, to fully understand the functionality and layout of the circuit board in question. Gerber format files are provided in American Standard Code for Information Interchange (ASCII) format, and are readable without the need for a translation program. In other words, the file is written in plain letters and numbers, not in binary or any other form which would be impossible for a human user to understand. There is software available that can display an image of the information contained in a Gerber format file.
The RS-274-X file type contains a complete description of the printed circuit board in and of itself. No external files are necessary to understand or supplement it. It can identify different planes on the board, positive images, and can describe any conceivable aperture shape without deviating from its standard ASCII layout. The RS-274-X files are originally created by either using electronic design programs or printed circuit board computer aided design programs.
One drawback to Gerber format files is that they do not contain information about the specific layer of the PCB they are referring to; this must be inferred from the other data in the file. This is usually not a major problem, but can be an inconvenience as individuals searching through the files will have to look through multiple files before locating the specific layer they are looking for. In spite of this, Gerber format files still remain the almost universal standard for the printed circuit board industry.