elementary OS is a computer operating system built on the Linux kernel. It is designed to run on any relatively new 32- and 64-bit desktop or laptop, whether Mac or PC.
Luna is based on Ubuntu 12.04 LTS. As such, anything that works with Ubuntu 12.04 should work equally as well with elementary OS Luna. It's available in both 32-bit (i386) and 64-bit (amd64) versions. Both versions are identical other than the target processor type.
Users may be able to install Luna on devices that do not meet these requirements, but the experience is likely to suffer.
elementary OS Luna ships with Linux kernel version 3.2.0. It's based on Ubuntu 12.04 LTS, so many of the default app versions are the same as in Ubuntu 12.04.
elementary OS Luna ships with the following apps preinstalled:
Thousands more can be installed in the Software Center