temp folders

When temporarily downloading, unpacking stuff some programs use different folders:
/root
/opt
/tmp

so what's the difference between them and should I just choose one of them?

 

Take a look here: http://www.debianadmin.com/linux-directory-structure-overview.html

I'd use /tmp for downloading and unpacking. But keep in mind that this directory is cleaned whenever you reboot the system (at least on Debian/Ubuntu).

 

Thank you very much for the url and your comment.

 

Any idea why lost+found folder is still on all distros? seems like it's never used and no reason for it anymore?

 

http://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/lostfound.html

 

Thank you very much. That was so helpful!