/joh'liks/ n.,adj. 386BSD
PORTING UNIX TO THE 386: A PRACTICAL APPROACH
William & Lynne Jolitz
In operation, directories in the root are reserved for temporary and persistant data, such as compiler temporary files and accounting records.
Operation: /tmp and /var
Once in operation, the /tmp directory is used to store temporary files from editors, formatters, compilers, and assemblers, as needed. /var is a directory that holds various short-term data, such as usage accounting, security logs, incoming electronic mail, crash dumps, printer spooling, and runtime program databases. Frequently, these two directories are separately mounted filesystems, especially on systems where these kinds of files take up much space.