There are a large number of file formats used in a GIS. Some of these formats are proprietary, which means that their structure is not public and that they are mainly used by specific software. Others are more open.
The main file formats are readable directly or after translation by different software. The shapefile format (.shp extension) by ESRI is one of the standards in vector mode. It is read by most software. Google’s KML/KMZ format is also becoming a standard. There are also programs that perform the translation from one format to another. Modern software tend to be able to read and combine all formats. Keep in mind that in order to avoid compatibility problems it is better harmonize sizes in a database, so you can easily change them. A conversion is thus necessary before working with the data.
[French: Fichiers (Format)]