This is a list of Linux distributions that can be run entirely from a computer's random-access memory (RAM), meaning that once the operating system (OS) has been loaded to the RAM, the media it was loaded from can be removed, and the distribution will run the personal computer (PC) from RAM only. This ability allows them to be very fast, since reading and writing data from and to RAM is far faster than on a hard disk drive or solid-state drive. Many of these operating systems will load from a removable media such as a Live CD or a Live USB stick. A "frugal" install can also often be completed, allowing loading from a hard disk drive instead.
This feature is implemented in live initial ramdisks (initramfs) and allows a user to run a live distro that does not run from RAM by default by adding <code>toram</code> to the kernel boot parameters.
Further, some distributions can be configured to run from RAM, such as Ubuntu, using the toram option included in the initial ramdisk Casper utility scripts.