Who is Shri Radha?
Shri Radha, daughter of King Vrishabhanu of Barsana, is Krishna's dearest beloved, honoured in devotional tradition as the highest form of pure love and devotion.
Answer
Shri Radha is the daughter of King Vrishabhanu and Mother Kirti of Barsana in Vraja. Her appearance is celebrated on the Ashtami of the bright fortnight of Bhadrapada, known as Radhashtami. She is Shri Krishna's dearest beloved and the foremost among the gopis.
In the devotional tradition, Radharani is seen not merely as a beloved but as the Lord's hladini shakti, the divine power of bliss. That is why her name is spoken before his in "Radhe Krishna" and "Radhe Shyam". Her love is completely selfless, and devotees regard her as the very ideal of bhakti.
It is worth noting that Radha is not named explicitly in the Shrimad Bhagavatam, although acharyas see her indicated in a special gopi in the Rasa Leela episode. Detailed accounts of her appear in the Padma Purana, the Brahma Vaivarta Purana, Jayadeva's Gita Govinda and the works of later devotional poets. She is worshipped with special devotion in traditions such as the Nimbarka, Gaudiya, Vallabha and Radhavallabha sampradayas.