So, those Naruto fans who said that Tobi is Obito because he is an Uchiha, and that he only has a right Sharingan eye, and the name Tobi is somewhat related to the name Obito.
The Naruto Manga 599 revealed the truth about Tobi. This happens when Naruto successfully broke the mask of Tobi. Tobi is Obito, the former teammate of Kakashi, and the one who gave him the left Sharingan eye.
I gues, the next Naruto Manga which is the chapter 600 will tell us how he survived the incident that large rocks crashed his body during the second shinobi world war in the battle of the Kannabi Bridge.