Short answers, pulled from the story.
The PLATO system launched in 1960 at the University of Illinois and offered early forms of social media features including Notes, TERM-talk instant messaging, Talkomatic online chat rooms, News Report crowdsourced newspapers, and Access Lists for user access control.
SixDegrees launched in 1997 and is often regarded as the first social media site with features like profiles, friends lists, and school affiliations inspired by the six degrees of separation concept.
As of 2023, as many as 4.76 billion people used social media representing about 59% of the global population according to Statista data.
Social media has been criticized for negative impacts on children and teenagers including exposure to inappropriate content, exploitation by adults, sleep problems, attention problems, feelings of exclusion, and various mental health maladies such as Facebook depression and low self-esteem.
In November 2024 the federal government passed the Online Safety Amendment Social Media Minimum Age Act 2024 introduced by the Albanese government banning people under age 16 from using most social media platforms effective December 2025.