Debian is a free (Operating System, OS) designed for your computer. The operating system is a collection of basic programs and tools that make computer operations, the most important part of the KERNEL. The core is the most important program in the computer, responsible for the scheduling work of the basic "holding home" and let you perform other programs. Debian uses Linux core, it is a completely free software, start writing by Linus Torvalds and supports thousands of programs all over the world. Most of the basic tools in the operating system are from the GNU program, and these tools are also free software.
One of the operating systems is Application Software: Some programs that help you complete your work, by editing documents to business transactions, playing more software by games. Debian has more than 1,500 packages (compiled software, and packing it to install) - all of them are free software.
The Debian system is a bit like a pyramid. In its substrate is Linux. Above is all basic tools, mainly from GNU. On it is all applications you performed on the machine, there are many from GNU. Debian's developer is better than architects and coordinators - they combine all things properly, carefully formulate a stable operating system: Debian GNU / Linux.
GNU / Linux design philosophy is to distribute its function with some small but multi-purpose components. Do you you can combine these fine components (programs) to achieve new features. Debian seems to be an eector SET: You can use it to build anything.
When you use an operating system, you will make a minimum spiritual time to complete your work. Debian is accompanied by a lot of tools to help you, but you must know what these tools do. Virtual consumption is attempted to use some things but finally give up, and it is very uncomfortable.