It is intended to appear as a mounted file system, but data is stored in volatile memory instead of a persistent storage device.
The idea behind tmpfs is similar in concept to a RAM disk, in that both provide a file system stored in volatile memory; however, the implementations are different.
[7] 4.2BSD introduced MFS,[8] a memory-based file system implemented by applying the existing FFS disk filesystem to a virtual memory region.
tmpfs, a memory filesystem implemented using conventional in-memory data structures in order to improve on the performance of MFS, was merged into the official NetBSD source tree on September 10, 2005;[9] it is available in 4.0 and later versions.
Since RAM is cleared upon reboot, tmpfs prevents systems from becoming too cluttered without requiring that the user manually delete temporary files.
In addition, storing files in RAM prevents disks from filling up too quickly and extends the life of flash-based storage by reducing the number of writes.