The first social media platform, to be widely accepted and used, was Six Degrees, launched in 1997. It allowed users to create a profile and make friends with other users, who were then connected to each other in a degree-based system. Though Six Degrees is considered the first large-scale social platform, there were other social media networks that predate it, such as The WELL, which was created in 1985 as a virtual community platform focusing on conversations.
It's interesting to note that online communities where a form of 'social media' existed as early as 1978 in the form of Usenet, a distributed bulletin board system where discussions took place. It can be considered the earliest form of social media, and is still widely used today.
Social media has dramatically changed communication since it's early beginnings and continues to evolve. From short 'microblogging' platforms such as Twitter, to image-based sites such as Instagram - social media has changed the way we communicate, and more so the way we engage with each other.
For more information about the History of Social Media, take a look at this Timeline of Social Media from MentorMate:
https://mentormate.com/blog/history-of-social-media-a-timeline/
