and not a programming one. It also means that the scripts will be saved and sent to the clients in plain text and won't be compiled
before, so you are able to take a look at the source code whenever you want. These source codes with the suffix ".js" are saved in every browsers cache and can be opened with a basic text editor like Windows' Notepad.
where the software is isolated from the rest of the system. So on the one hand the scripts can do no damage and on the other one the effects can be recorded. So it is warranted that the scripts will be executed in isolation and that they can only access objects which are part of the browser and not the user's file system for example.