A file with .glb extension is a globally sharable file generated and used by the AGI Systems Tool Kit (STK) software. It contains 3D globe information that can be shared with other users to be used in their projects. AGI systems' STK software is used to simulate aerospace missions, defense systems, and telecommunication systems. GLB is the standard file format for STK and many different 3D models such as .gltf can be converted to this format. GLB files can be opened with AGI Simulation Toolkit software as well as any text editor.
GLB File Format - More Information
GLB files store information about textures, images, and other files that are used in a globe for a project. References to the location of the linked files are stored in the GLB files and these additional files must also be shared with other users while sharing the GLB globe file for proper loading. GLB files store all this information in plain text files that can be opened with any text editor.