Consider a browser cache. /tmp is not guaranteed to be preserved between program invocations[1]. /var/tmp [2] might be a better place. /var/cache [3] is intended for exactly this kind of thing.
Unfortunately, it can be far more useful for an administrator in a multi-user setup to want user-specific caches in home directories. That way, you get all of the infrastructure for managing user data for free, like quotas.
Also note: if you're considering putting data into /tmp or /var/tmp, please honor the TMPDIR environment variable, if it is set[4].
Consider a browser cache. /tmp is not guaranteed to be preserved between program invocations[1]. /var/tmp [2] might be a better place. /var/cache [3] is intended for exactly this kind of thing.
Unfortunately, it can be far more useful for an administrator in a multi-user setup to want user-specific caches in home directories. That way, you get all of the infrastructure for managing user data for free, like quotas.
Also note: if you're considering putting data into /tmp or /var/tmp, please honor the TMPDIR environment variable, if it is set[4].
[1]: http://www.pathname.com/fhs/pub/fhs-2.3.html#TMPTEMPORARYFIL...
[2]: http://www.pathname.com/fhs/pub/fhs-2.3.html#VARTMPTEMPORARY...
[3]: http://www.pathname.com/fhs/pub/fhs-2.3.html#VARCACHEAPPLICA...
[4]: http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_...