UBUNTU

history-
It is one kind os . which works like a linux.
Ubuntu is designed primarily for desktop use, although netbook and server editions exist as well.
Web statistics suggest that Ubuntu's share of Linux desktop usage is about 50%
Ubuntu is a fork of the Debian project's codebase. The original aim of the Ubuntu team was to create an easy-to-use (freedom for users rather than freedom for programmers) Linux desktop with new releases scheduled on a predictable six-month basis, resulting in a more frequently updated system.
The latest LTS release is Ubuntu 10.04 (Lucid Lynx), released on 29 April 2010, while the latest normal release is Ubuntu 11.04 (Natty Narwhal), released on 28 April 2011.

Features-

Ubuntu is composed of many software packages, the vast majority of which are distributed under a free software license. The only exceptions are some proprietary hardware drivers.The main license used is the GNU General Public License (GNU GPL) which, along with the GNU Lesser General Public License (GNU LGPL), explicitly declares that users are free to run, copy, distribute, study, change, develop and improve the software. On the other hand, there is also proprietary software available that can run on Ubuntu. Ubuntu focuses on usability, security and stability.
The Ubiquity installer allows Ubuntu to be installed to the hard disk from within the Live CD environment, without the need for restarting the computer prior to installation. Ubuntu also emphasizes accessibility and internationalization to reach as many people as possible. Beginning with 5.04, UTF-8 became the default character encoding,which allows for support of a variety of non-Roman scripts. As a security feature, the sudo tool is used to assign temporary privileges for performing administrative tasks, allowing the root account to remain locked, and preventing inexperienced users from inadvertently making catastrophic system changes or opening security holes.
Ubuntu, unlike Debian, compiles their packages using gcc features such as PIE and Buffer overflow protection to harden their software.These extra features greatly increase security at the performance expense of 1% in 32 bit and 0.01% in 64 bit.

System requirements-

Current Minimum Requirements	Server	Desktop
Processor (x86) with the i686 instruction set	300 MHz	1 GHz
Memory	128 MB	384 MB
Hard Drive (free space)	1 GB	5 GB
Monitor Resolution	640×480	1024×768