A GBR file contains printed circuit board (PCB) design data in Gerber format, which is an industry-standard file format supported by many PCB design systems. It contains instructions for drilling and milling the board and includes information about the board's electrical connections. GBR files are commonly used by PCB professionals to securely exchange image, drill, and rout data from design software to manufacturing machines.

The Gerber format is simple and compact, storing data that precisely describes a 2D image of a PCB and metadata required for the fabrication of a PCB. The GBR format was originally developed by Gerber Systems but is now maintained by Ucamco.

Image brush used by the GNU Image Manipulation Program (GIMP), an open source image editing application; stores the description, bitmap image, and the spacing for the brush; used for storing graphics that can be repeatedly painted on a GIMP image canvas.

GBR files are used to store both the default program brushes as well as custom user brushes. Some default brushes are located in the /share/gimp/2.0/brushes/ directory of a GIMP installation.