Twitter / X is where I occasionally check news and recent events.

Quora is mostly maintained for archival purposes. For a number of years after moving abroad and taking down my old website, I would occasionally write something about a question or topic that seemed interesting.

Github - There is an account to communicate with those who host code there.

Goodreads - Used to inventory books currently on the shelf, and research others.

As for other popular platforms, watch "The Social Dilema".