Esri ArcGIS is one of the most well-known commercial GIS applications.
In ArcGIS, separate map layers are saved as Shapefiles. Multiple map layers can be stored in a relational Geodatabase. A File Geodatabase usually looks like a folder with a .gdb extension in the folder name. This folder contains multiple files with generic file names and extensions such as .gdbindexes; .gdbtable.
GDB is designed as an efficiently structured storage for GIS data, optimized for use. Nevertheless, support outside of Esri software is limited and it is not easy to see which map layers are present in the Geodatabase.
For the long term and to promote interoperability, it is therefore recommended to store the contents of a Geodatabase in separate map layers, each in an open, well-supported and robust text file.
GDB is a non-preferred format for file type GIS.