Temporary files can be created by user programs. On my machines, I made /tmp an in memory file system and also disallow execution or setuid/gid in this directory as much malware tries to abuse it in this manner.

This is outdated, since /bin, /sbin and /lib now should be merged with their /usr counterparts

What’s the difference between run time program data and temporary files? Is /tmp just for system level processes but not for user space?