Kubuntu

Kubuntu ( /kuːˈbuːntuː/ koo-BOON-too) is an official derivative of the Ubuntu operating system using the KDE Plasma Desktop instead of the Unity graphical environment. Blue Systems took over as sponsor from Canonical Ltd., and Kubuntu will retain use of Ubuntu project servers. It is part of the Ubuntu project and uses the same underlying system. It is possible to install both the KDE Plasma Desktop (kubuntu-desktop) as well as the Unity desktop (ubuntu-desktop) on the same machine. Every package in Kubuntu shares the same repositories as Ubuntu. It is released regularly on the same schedule as Ubuntu.

Read more about Kubuntu:  Name, Comparison With Ubuntu, Gallery, History, Releases, System Requirements, Deployments