Ubuntu 15.04
http://www.ubuntu.com/

Welcome to the Vivid Vervet edition of the Ubuntu Linux operating system, a free and open source distribution of Linux derived from the highly acclaimed and award-winning Debian GNU/Linux OS.

This edition uses the Unity desktop environment and includes a great number for improvements over previous releases of the world’s most popular free operating system. It will be supported with security patches and software updates until October 2015.
Distributed as 32-bit/64-bit Live DVDs