Vedanta is made of two words- ‘Veda’ and ‘ant’, i.e. the end of the Vedas. This school upholds the philosophies of life as elaborated in the Upanishads. The oldest text that formed the basis of this philosophy was Brahmasutra of Badrayana that was written and compiled in 2nd century BCE. The philosophy propounds that Brahma is the reality of life and everything else is unreal or Maya.
Furthermore, the Atma or the consciousness of self is similar to the Brahma. This argument equalizes Atma and Brahma and if a person attains the knowledge of the self, he would automatically understand Brahma and would achieve salvation.
This argument would make Brahma and Atma indestructible and eternal. There were social implications of this philosophy, i.e. that true spirituality was also implicit in the unchanging social and material situation in which a person is born and placed.
But the philosophy evolved in the 9th century AD through the philosophical intervention of Shankaracharya who wrote commentaries on the Upanishads and the Bhagavad Gita. His changes led to the development of Advaita Vedanta. Another major philosopher of this school was Ramanujan who wrote in the 12th century AD. His intervention led to some differences in Vedanta school: The Vedanta theory also gave credence to the Theory of Karma.
They believed in the theory of Punarjanama or rebirth. They also argued that a person would have to bear the brunt of their actions from the previous birth in the next one. This philosophy would also allow people to argue that sometimes they suffer in their present birth because of a misdeed of the past and the remedy is beyond their means except through the finding of one’s Brahma.