The Mangekyō Sharingan (万華鏡写輪眼; Literally meaning "Kaleidoscope Copy Wheel Eye"), noted to be the "heavenly eyes that see the truth of all of creation without obstruction" (天壌の理を掌握せし瞳, tenjō no kotowari wo shōaku seshi hitomi),1 is an advanced form of the Sharingan that has only been activated by a handful of Uchiha.2 It was also awakened by Kakashi Hatake — a non-Uchiha.3
Mangekyou Sharingan is translated as Kaleidoscope Copy Wheel Eye. It is a higher form of the Uchiha clan's sharingan. The basic sharingan will enable the user to memorize any technique that it has been a witness to including ninjutsu, genjutsu, and taijutsu techniques it can also enable the user to see through and illusionary technique. With the Mangekyou Sharingan activated, one major advantage is to be able to use the three most powerful jutsu possible, tsukuyomi, amaterasu, and susanoo. The disadvantage of the Mangekyou Sharingan is, it causes the deterioration of the eyes.
The Mangekyou Sharingan (literally Kaleidoscope Copy Wheel Eye in Japanese) is the 4th and highest level of the Uchiha clan's Sharingan (a technique from the wonderful anime, "Naruto"). Aquiring it signifies complete mastery of the Sharingan, which allows usage to techniques such as Amaterasu and Tsukiyomi. The secret of the Mangekyou Sharingan is that only those from the Uchiha clan who have achieved the 3rd level of Sharingan (3 teardrops in both eyes), and have killed their best friend, may use it. So far in the Naurto manga, Uchiha Itachi is the only one who has been revealed that has achieved such a level.