Puppy Linux is an operating system and family of light-weight Linux distributions that focus on ease of use and minimal memory footprint. The entire system can be run from random-access memory with current versions generally taking up about 600 MB (64-bit), 300 MB (32-bit), allowing the boot medium to be removed after the operating system has started. Applications such as AbiWord, Gnumeric and MPlayer are included, along with a choice of lightweight web browsers and a utility for downloading other packages. The distribution was originally developed by Barry Kauler and other members of the community, until Kauler retired in 2013. The tool Woof can build a Puppy Linux distribution from the binary packages of other Linux distributions.

History
Barry Kauler started Puppy Linux in response to a trend of other distributions becoming stricter on system requirements over time. His own distribution, with an emphasis on speed and efficiency and being lightweight, started from "Boot disk HOWTO" and gradually included components file-by-file until Puppy Linux was completed. Puppy Linux started as Vector Linux based until it became a fully independent distribution.

Features
Puppy Linux is a complete operating system bundled with a collection of applications suited to general use tasks. It can be used as a rescue disk, a demonstration system that leaves the previous installation unaltered, as an accommodation for a system with a blank or missing hard drive, or for using modern software on legacy computers.

Puppy's compact size allows it to boot from any media that the computer can support. It can function as a live USB for flash devices or other USB mediums, a CD, an internal hard disk drive, an SD card, a Zip drive or LS-120/240 SuperDisk, through PXE, and through a floppy boot disk that chainloads the data from other storage media. It has also been ported to ARM and can run on a single board computer such as the Raspberry Pi.

Puppy Linux features built-in tools which can be used to create bootable USB drives, create new Puppy CDs, or remaster a new live CD with different packages. It also uses a sophisticated write-caching system with the purpose of extending the life of live USB flash drives.

Puppy Linux includes the ability to use a normal persistent updating environment on a write-once multisession CD/DVD that does not require a rewritable disc; this is a unique feature that sets it apart from other Linux distributions. While other distributions offer live CD versions of their operating systems, none offer a similar feature.

Puppy's bootloader does not mount hard drives or connect to the network automatically. This ensures that a bug or even unknowingly incompatible software won't corrupt the contents of such devices.

Puppy Linux offers a session save on shutdown. Since Puppy Linux fundamentally runs in RAM, any files and configurations made or changed in a session would disappear otherwise. This feature enables the user to either save the contents to a writable storage medium, or write the file system to the same CD containing Puppy, if "multisession" was used to create the booted CD and if the disc drive supports burning. This applies to CD-Rs as well as CD-RWs and DVDs.

It is also possible to save all files to an external hard drive, USB stick, or even a floppy disk instead of the root file system. Puppy can also be installed to a hard disk.