Ardhanarishvara (Sanskrit: अर्धनारीश्वर, Ardhanārīśvara) is a composite androgynous form of the Hindu god Shiva and his consort Parvati (also known as Devi, Shakti and Uma in this icon). Ardhanarishvara is depicted as half male and half female, split down the middle. The right half is usually the male Shiva, illustrating his traditional attributes.
The earliest Ardhanarishvara images are dated to the Kushan period, starting from the first century CE. Its iconography evolved and was perfected in the Gupta era. The Puranas and various iconographic treatises write about the mythology and iconography of Ardhanarishvara. While Ardhanarishvara remains a popular iconographic form found in most Shiva temples throughout India, very few temples are dedicated to this deity.
Ardhanarishvara represents the synthesis of masculine and feminine energies of the universe (Purusha and Prakriti) and illustrates how Shakti, the female principle of God, is inseparable from (or the same as, according to some interpretations) Shiva, the male principle of God. The union of these principles is exalted as the root and womb of all creation. Another view is that Ardhanarishvara is a symbol of Shiva's all-pervasive nature. [Source -Wikipedia].