Visitor Counter

I understand about the 3 type of local storage (local, session, memory), at least I think I do. However, when looking at keeping an ongoing count for the number of visitors, where can I store the current count ?
Example if they do not have a “visited” indicator for SESSION, then I want to get the latest count, increase by one, save the new number, then display on the screen. I understand that in this scenario, if they came back to the site a couple of days later, they would be counted again. This is what I want. BUT, …
Where can I store the “count to date” so that other visitors get counted as well?
Thank You.