I'm not asking for a legal definition. This is Hacker News; in looking for a definition that would enable hackers to correctly classify things most of the time.
I think there is probably some combination of the following aspects:
-Content is user-generated
-Content is curated by the company (i.e., users don't have the ability to fully turn off what is shown to them)
-Content is not universal (i.e., users don't see the same thing)
