Application directory
The application directory stores
The directory structure is self-explaining.
You can delete for example the configuration-file; it will be generated new with the defaults.
It is recommended to create backups from this directory, before you install a new version.
Windows
Installation by Zip-package
Application directory is the same as the unpacked factorio directory.
For example, if you unpacked the zip to
C:\Factorio
Then your saves can be found in
C:\Factorio\saves
and mods in
C:\Factorio\mods
Installation via Installer
Installation package follows UAC. For that case the factorio directory is where you install it (Program files by default) and the user data (saves, player data etc) are stored in
C:\Users\<username>\AppData\Roaming\Factorio
Windows Vista and newer (UAC active):
%appdata%\factorio
MacOSx
The application should be by default installed in the Apps-folder.
Whereas the data is stored under
/users/<replace with your username>/Library/Application Support/factorio
Which is equivalent to
~/Library/Application Support/factorio
You can type in this into the finder (press SHIFT-COMMAND-G for goto folder) and put in exactly this line.
If you still don't see this folder it might be invisible for you. Search in the internet for for example about "make library folder visible macos".
Example link: http://finerthings.in/featured/lion-library-folder-visible/
Linux
Data is stored under
~/.factorio
Changing the application directory
It is possible to change the application directory location for Factorio. This can be done by editing the location of the "write-data" entry in the file config.ini. This affects the location of mods, scenario and temp.
If you want to move only the location of your save files you can change the the save directory using symlinks.