Multi-user, Multi-tasking.

[Albert DE WINT <adwint pandora be>]

Hi,

I suppose this is be a VERY basic question.  Unfortunately, I can't
find the answer in any manual.

I understand Linux is fully multi-user, multi-tasking. 
How can I log off, in order to allow another user to log-on the same PC,
without my running background tasks, being interrupted or shut-down.

Maybe I should lock my account (without logging out), and allow another
user to go ahead, without interfering in my applications?

(Before I forget, this is a stand-alone PC, obviously.)

Thank you for answering this very simple question.

Albert