A token is a unique identifier that allows an application or user to access some part of an API. It is basically a complex string that is generated and provided to an application accessing the services provided by the API. In our case, essentially, a token allows an authenticated user access to private or password protected REST services through the ArcGIS REST API.
In order to see the output of an ArcGIS REST API token, we can see the response by passing the parameters it takes through an URL. Navigate to the browser and enter this URL: https://www.arcgis.com/sharing/generateToken?username=youruser&password=yourpassword&referer=https://www.arcgis.com&f=json
Replace youruser and yourpassword with your actual username and password for the ArcGIS Online account you have or set up earlier in the book. When you enter this URL, because we passed f=json...