Ask HN: What was it like to use BBS?

I want to understand how the experience was

what was the cost involved

what were the entry barrier for an average person to join

How similar was it to current social media networks

How big the industry around it actually become

From a tech point of view what do you think were the major breakthroughs and what made it to the internet we see today.

I have watched the documentary www.bbsdocumentary.com , so I have some context but want some more anecdotes if I can :)