• A Hindu theologian, philosopher, and one of the most important exponents of the Sri Vaishnavism tradition within Hinduism.
• His philosophical foundations for devotionalism were influential to the Bhakti movement.
• Rāmānuja is famous as the chief proponent of Vishishtadvaita subschool of VedāntaRāmānuja is famous as the chief proponent of Vishishtadvaita subschool of Vedānta.
• His Vishishtadvaita (qualified monism) philosophy has competed with the Dvaita (theistic dualism) philosophy of Madhvāchārya, and Advaita (monism) philosophy of Ādi Shankara, together the three most influential Vedantic philosophies of the 2nd millennium.
• Rāmānuja‘s philosophical foundation was qualified monism, and is called Vishishtadvaita in the Hindu tradition.
• His ideas are one of three subschools in Vedānta, the other two are known as Ādi Shankara’s Advaita (absolute monism) and Madhvāchārya’s Dvaita (dualism).

Source: Wiki