Linux From Scratch describes the process of creating your own Linux system from scratch from an already installed Linux distribution, using nothing but the source code of software that you need.
From the author's introduction: "Having used a number of different Linux distributions, I was never fully satisfied with either of those. I didn't like the way the bootscripts were arranged, or I didn't like the way certain programs were configured by default and more of those things. I came to realize that when I want to be totally satisfied with a Linux system, I have to build my own Linux system from scratch. Ideally only using the source code. No pre-compiled packages of any kind. No help from some sort of cdrom or bootdisk that would install some basic utilities. You would use your current Linux system and use that one to build your own.
This, at one time, wild idea seemed very difficult and at times almost impossible. The reason for most problems were due to my lack of knowledge about certain programs and procedures. After I sorted out all kinds of dependency problems, compilation problems, etcetera, a manually Linux system was created and fully operational. I called this system and LFS system which stands for Linux From Scratch."