What is “back” on a dynamic page like Reddit, Facebook or even this site? If “back” means “show me exactly what I last saw” it might mean you are showing stale

What is “back” on a dynamic page like Reddit, Facebook or even this site? If “back” means “show me exactly what I last saw” it might mean you are showing stale data. I dunno. Shit ain’t easy once you think about it for a while. If all you have is a static unchanging set of items… might as well just use old school pagination! At least in my opinion. It’s when the list of items is constantly changing that things get interesting.