Defining a coordinate system for data
You now know how to assign and change the coordinate system used in a map. Maps are not the only things that are assigned a coordinate system. Our data is also assigned a coordinate system, or at least it should be. If your data is not assigned a coordinate system, then ArcGIS Pro may not be able to display the correct location with all your other data. This is also true if your data is assigned the wrong coordinate system.
Where is the coordinate system information stored within your data? Well, this depends on what type of data you are working with. If it is a feature class stored in a geodatabase, then the coordinate system information is stored within the geodatabase itself. If you are working with shapefiles, then the assigned coordinate system is stored in a file with a .prj file extension.
If you are working with CAD data, meaning .dwg, .dxf, or .dgn files, then you may also need a .prj file for ArcGIS Pro to know what coordinate system...
