The application folder contains the executable files used when running Arduino. The location and structure of these files depend on the system. The default installations paths are: Linux: See Open the Arduino IDE installation folder. Generally, the contents of this folder should not be changed.

It is possible to use the Arduino IDE to open and edit libraries: Add a dummy .ino file to the folder containing the library files you want to edit with the Arduino IDE. The .ino filename must match the folder name. This allows the Arduino IDE to open the library source files as if they were a sketch.

If you go into your file directory system and open up the Arduino Sketchbook folder (again, named “Arduino” by default), you may see a bunch of folders that you didn’t make. This is because every Arduino file must be inside a folder that has the same name as the file (there are some exceptions to this that we’ll talk about in a moment).

The .arduinoIDE folder contains configuration files like settings.json and arduino-cli.yaml. Default location: This folder is only used by Arduino IDE 2. The arduino-ide folder contains various temporary files. Removing this folder can sometimes resolve problems with Arduino IDE.