Everything that happens within an ADRIFT adventure is the result of a task. Tasks do things. All tasks have a set of restrictions (conditions that must be met in order for the task to run) and a set of actions (things that will be carried out if the task runs).
Whenever you type something at the cursor in Runner, that command is "parsed". The way ADRIFT does this is by pattern matching the command against a set of known phrases. The way you define this command is to use a General task. In other words, General tasks allow you to create new verbs that ADRIFT understands.
Specific tasks allow you to run special cases for General tasks, for example, if you wanted something different to happen when you used a particular object in a task.
System tasks are simply ones that are not triggered directly by what the user types on the command line.
All three tasks types share most of their functionality (see Common traits). The different task types simply alter how and when the task is triggered.