Ramanuja, also known as Sri Ramanujacharya, was a prominent Hindu philosopher and theologian who lived in the 11th and 12th century in South India. He is considered to be one of the most important proponents of Vishishtadvaita Vedanta, a school of Hindu philosophy that emphasizes on the concept of qualified non-dualism. Ramanuja's contributions to Vishishtadvaita Vedanta have greatly shaped and influenced the understanding of this philosophy.

One of Ramanuja's major contributions to Vishishtadvaita Vedanta is his commentary on the Brahma Sutras, called the Sri Bhashya. This commentary is considered to be one of the most authoritative texts on Vishishtadvaita Vedanta and provides a detailed explanation of the key concepts and principles of this philosophy. Ramanuja's commentary also incorporates the teachings of previous scholars and philosophers, making it a comprehensive and well-rounded text.

Another significant contribution of Ramanuja is his concept of 'Vishnu Tattva', which refers to the ultimate reality or the supreme being in Vishishtadvaita Vedanta. According to Ramanuja, Vishnu is the supreme being who is both the material and efficient cause of the universe. He believed that the individual souls (jivas) are eternally dependent on Vishnu and can attain liberation only through surrendering to him. This concept of Vishnu Tattva is central to Vishishtadvaita Vedanta and sets it apart from other schools of Hindu philosophy.

Ramanuja also introduced the concept of 'Sarira-Sariri Bhava', which means the relationship between the body and the soul. According to him, the individual soul is the 'Sariri' (possessor) and the body is the 'Sarira' (possessed). This concept helps in understanding the concept of liberation, where the individual soul realizes its true nature and its relationship with Vishnu.

Furthermore, Ramanuja's teachings also emphasized the importance of devotion (bhakti) in attaining liberation. He believed that devotion to Vishnu is the most effective way to overcome the cycle of birth and death and attain moksha (liberation). This emphasis on devotion has greatly influenced the practice of Hinduism and has led to the development of various devotional practices and rituals.

Ramanuja's contributions to Vishishtadvaita Vedanta also include his teachings on the nature of the universe and the individual self. He believed that the universe is a manifestation of Vishnu and the individual self is a part of the supreme self. This understanding helps in realizing the unity and interconnectedness of all beings.

In conclusion, Ramanuja's contributions to Vishishtadvaita Vedanta have greatly enriched and expanded the understanding of this philosophy. His teachings have been instrumental in shaping the beliefs and practices of Hinduism and continue to be relevant and influential even today