Vishishtadvaita is a school of Hindu philosophy that was founded by Ramanujacharya in the 11th century. It is a branch of Vedanta, which is one of the six main schools of Hindu philosophy. The term Vishishtadvaita is derived from the Sanskrit words "vishishta" meaning qualified or special, "advaita" meaning non-dualism, and "vaita" meaning unity. Therefore, Vishishtadvaita can be translated as "qualified non-dualism" or "unity with distinctions."

According to Vishishtadvaita, the ultimate reality is Brahman, the supreme consciousness or God. However, unlike other schools of Vedanta, Vishishtadvaita believes that the individual souls (jivatmas) are not separate from Brahman, but rather, they are a part of Brahman. This concept is known as "Brahman-atmaikya," or the unity of Brahman and the individual soul.

Vishishtadvaita also emphasizes the concept of "Bhakti," or devotion, as the means to achieve moksha (liberation from the cycle of birth and death). It teaches that through devotion and surrender to God, one can attain unity with Brahman and ultimately, achieve moksha.

One of the key principles of Vishishtadvaita is the concept of "Sariraka-Sariri-Bhava," which means the relationship between the body (Sarira) and the soul (Sariri). According to this principle, the individual soul is dependent on Brahman, just as the body is dependent on the soul. This relationship is not one of complete separation, but rather, it is a relationship of inseparable dependence.

Another important aspect of Vishishtadvaita is the concept of "Brahman-nirguna-saguna-vada," which means the belief that Brahman is both without qualities (nirguna) and with qualities (saguna). This means that while Brahman is ultimately formless and attributeless, it can also manifest itself in various forms and qualities for the benefit of the devotees.

In Vishishtadvaita, the world is seen as a manifestation of Brahman, and therefore, it is not considered as an illusion (maya) as in other schools of Vedanta. The world is seen as a means for the individual soul to attain moksha through devotion and service to God.

In conclusion, Vishishtadvaita is a school of Hindu philosophy that emphasizes the unity of the individual soul with Brahman, while also acknowledging the distinctions and qualities of Brahman. It teaches the path of devotion and surrender to God as the means to achieve moksha and attain ultimate unity with Brahman.