Debian is a free operating system (OS) for your computer. An operating system is the set of basic programs and utilities that make your computer run. At the core of an operating system is the kernel. The kernel is the most fundamental program on the computer: It does all the basic housekeeping and lets you start other programs. Debian uses the Linux kernel, a completely free piece of software started by Linus Torvalds and supported by thousands of programmers worldwide. A large part of the basic tools that fill out the operating system come from the GNU Project, and these tools are also free.