Sorry if this is a dumb question.

I've recently had problems with intermittent failures to log in to admin. I get the 'there was a security problem with your login' message.

My service provider's engineer has made some changes for me but did query the fact that I had an incorrect path (to a non existent directory) in my sessions /session directory.

As far as I know I've never changed this previously, so assume that it has made no difference in the past ?? (I have though, now corrected the setting to a 'correct' path)

Therefore my dumb question.

Please can someone tell me what exactly should be being saved in this folder. What is it's purpose and should I know about it.
Many thanks