With django-activity-stream one can create activity streams (what were the latest things done?) like in Facebook, Twitter, or any other social network.
What is the difference and what are the use cases of action object and target there?
As of http://activitystrea.ms/ :
[Object] describes the primary object of the activity. For instance, in the activity, "John saved a movie to his wishlist", the object of the activity is "movie".
[Target] describes the target of the activity. The precise meaning of the activity's target is dependent on the activities verb, but will often be the object the English preposition "to". For instance, in the activity, "John saved a movie to his wishlist", the target of the activity is "wishlist".
Think of it as an english sentence :
Actor Verb Object Target
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Paul | uploaded | an artwork | to his collection
Jane | added | an event | to her personal calendar
Aidas | asked | a question | on django discussion