Interoperability means the capability of two or more systems to exchange information and use/interpret the information shared without knowledge of the data structure. According to the online ESRI GIS Dictionary:
The interoperability is required for a GIS user using software from one vendor to study data compiled with GIS software from a different provider.
There are two important aspects of data interoperability in GIS:
Spatial data type (for example, GIS, CAD, raster, XML, and LiDAR)
Spatial data format (for example, shapefile, DWG, ECW, GML, and XYZ)
Data standards support you in dealing with data interoperability issues. Standards refer to formats, data models, or both.
Note
Here you have some examples of international and national spatial standards:
ISO/TC 211 Geographic information/Geomatics: http://www.iso.org
Open Geospatial Consortium: http://www.opengeospatial.org
Ordnance Survey MasterMap: http://www.ordnancesurvey.co.uk