Extensions allow you to connect to hardware devices or web services.
In any project, click the More Blocks category and choose Add an Extension.
If you have LEGO WeDo 2.0, see LEGO WeDo 2.0 Setup.
If you have LEGO WeDo 1.0 or a PicoBoard, see LEGO WeDo 1.0 or Picoboard Setup.