A RAM disk is a block of RAM (Random Access Memory) that a computer treats as if it were a locally attached Hard Disk Drive. It is sometimes referred to as a virtual RAM drive or software RAM drive.
Because the speed of RAM is much faster than most other kinds of storage, files on a RAM disk can be accessed more quickly. Also because the storage is actually in RAM, it is volatile memory and will be lost when the computer powers off. This is sometimes desirable, for example, when working with a decrypted copy of an encrypted file. The decrypted, potentially sensitive data, disappears when the machine restarts.
In many applications, data is copied to a RAM disk from other media for much faster access. With RAM drive emulation these virtual drives can be more than 1000 times faster than your local hard drive. They appear to your system and applications as a standard disk volume where you can read and write files.