For the Windows build, the first one is .pdb files. Those are extremely useful for debugging and people who have worked with Visual Studio probably know already a lot about them.
PDBs are basically files containing debug symbols of a specific executable. They can be very helpful in debugging because a dev can distribute a typical release executable (even with all debug info stripped) and keep the corresponding .pdb somewhere locally. If one wants to submit a crash report, all they have to do is find the crash dump generated by Windows (typically found as <localappdata>/CrashDumps/oolite.exe.XXXXX) and upload it somewhere. The dev holding the .pdb can take the dump file and use the .pdb to pinpoint the exact point of failure. The analysis can be done either on Visual Studio (although I haven't tested that) or in external debugging utilities, like Microsoft WinDbg, which is available at the MS Store for free.
To create a .pdb just run e.g.
make debug=no pdb=yes. The pdb will be created inside obj.win.spk.Important: A .pdb has one and only one corresponding executable that it is able to debug. If the code changes and a new exe is created then a new pdb must be created too, as the old one will no longer be good for debugging.
