Definition: RAM Disk is also known as RAM Drive. A RAM disk is not a disk at all; It is a program which takes the portion of the system memory (RAM, in the form of memory chips) and uses it as a disk drive. You can create a larger RAM disk, if your computer has more RAM.
A RAM disk can also take the form of a hardware device or a virtual disk. RAM drive makes use of regular RAM instead of accessing the data bus. Sometimes RAM drive also makes use of the compressed file system, so that compressed data can access but without decompressing the compressed data.