When I do a ulimit -n I got 256, I assume it means I can open 256 files at the sametime. Does it means I can open 256 files with one single session? or all sessions?

For example, I logined to my server with username "abc" (via putty/ssh), and open 200 files, with the session still running, I logined to the same server again with the same username "abc" (via putty/ssh), I can open only another 56 files? or I can open another 256 files?

Lastly, does this limit also restrict number of http connections? e.g. with the above example, I have opened 200 files, and then I use "wget" or "curl" to make http connections.

Thanks