.ged - Genealogical Event Data format. Native format for exchanging lineage-linked data between various genealogy programs.

.gid - Help index files created when Windows help (.hlp) files are accessed to provide a faster search.

.gif - Graphics Interchange Format. A data stream-oriented file format used to define the transmission protocol of LZW-encoded bitmap data. Very popular type of graphic used widely on the Internet. ( filename extension )

.gks - Graphics Kernel System format. Standard specifying the input and output primitives for displaying 2D and 3D graphical data. Although .gks has no native file format, the .cgm format is often closely associated with its use.

.gl - An animation archive format created by the GRASP (Graphical System for Presentation) program that generates large files and is resolution-dependent.

.gmf - Computer Graphics Metafile. Another file extension used interchangeably with .cgm

.grib - Gridded Binary format. Standard format for the storage and interchange of meteorological data.

.grp - Group format. Windows file that groups together objects or other files. ( filename extension )

.gry - Raw Grey graphics format. ( filename extension )

.gz, .gzip - Gnu Zip file format. UNIX compression utility that compresses a single file at a time. ( filename extension )