GB files exist as 2 different types. Please find information about each of them below.
Type 1: Game Boy ROM File
You can open a GB file with Game Boy emulators like VisualBoyAdvance, BGB, and KiGB. Select File → Open GB... in VisualBoyAdvance. GB files contain copies of Nintendo Game Boy video game cartridges....
You can open a GB file with Game Boy emulators like VisualBoyAdvance, BGB, and KiGB. Select File → Open GB… in VisualBoyAdvance. GB files contain copies of Nintendo Game Boy video game cartridges. These ROM images work in emulators on Mac OS and Windows devices. Basic Boy and 4 other programs support the GB format.
GB stores Nintendo Game Boy data. We know of 2 GB uses: Nintendo game files and gene sequence records. Game files are more common.
Emulators let GB games play on computers. First, get a GB ROM file, an exact copy of a Game Boy cartridge. Then use software like Visual Boy Advance to emulate the Game Boy on your computer. The emulator displays and runs the GB game file.
Other GB formats exist too. GenBank GB files store DNA sequences for genome research. CEDIT GB files hold Chinese dictionary data. Some programs use GB for images. But most GB files are Nintendo game ROMs.
VisualBoyAdvance
RetroArch