Open GDB File
GDB extension files present, up to now, two applications of a different nature, namely:
Garmin MapSource
A GDB extension file is a database file created by MapSource, a GPS route editing and trip planning application.
MapSource is Garmin software for viewing maps, routes, waypoints, and tracks.
These maps and routes are transferred to or from a Garmin GPS device through MapSource.
MapSource is included with some Garmin GPS devices and with some Garmin mapping products. MapSource is compatible with Windows.
In this case, the GDB file contains waypoints, routes, and tracks just to be transferred to a Garmin navigation device.
GDB files are similar to GPX files that are universally transferable.
InterBase
In this use case, the GDB file is a database file created with Borland InterBase.
InterBase is a relational database management system developed and marketed by Embarcadero Technologies, originally created by Borland.
Thus, GDB is the default extension used by InterBase versions prior to InterBase 7.0.
It is important to note that databases created with InterBase 6.5 and earlier have a 2GB file size limit.
From InterBase version 7.0 and later, IB files are used to save database files, instead of GDB files.