The sharingan literally meaning 'copy wheel eye' is the dōjustu kenkkei genkai of the Uchiha clan in the series Naruto.
progression[]
The sharingan has seven progressions(only in manga) and six(in the anime).
The first three are based on magatama these give them their shape.
MongekyouAfter the thrid form is achieved a Uchiha can either gain the mongekyou by, killing his/her friend or by having enought hatred in their system as the sharingan are powered by hate in the minds of Uchihas.