Linux distributions (often abbreviated as distros) are made of the Linux kernel and a collection of applications. The operating system will be made up of the Linux kernel and, usually, a set of libraries and utilities from the GNU project, with graphics that come from the X Window System. Distributions that are made to be small may not contain big window systems full of features like KDE or GNOME, but use small window systems like busybox, uclibc or dietlibc. There are more than three hundred Linux distributions. Most of those are in still in development, being improved and changed constantly.