The ganas are a threefold classification of the twenty-seven nakshatras, the lunar mansions of Indian astronomy, into deva, manushya and rakshasa, divine, human and demonic. Deva gana covers nine of the twenty-seven, among them Ashwini, Mrigashira, Punarvasu, Pushya, Hasta, Swati, Anuradha, Shravana and Revati, and the temperament it denotes is gentle, refined, generous and inclined to serve others; the classical descriptions associate it with sattva, the clear and balanced of the three gunas. The classification is not about the deity of the nakshatra but about the disposition of a person born under it, and its principal use is practical rather than descriptive: it is one of the twelve kootas or points of agreement in the Ashtakoota system by which the compatibility of a prospective bride and groom is assessed in much of India.
The classification is set out, along with the rest of nakshatra based matching, in the Brihat Parashara Hora Shastra, the foundational compendium of Vedic natal astrology traditionally ascribed to the sage Parashara. Within the gana koota, worth six of the Ashtakoota system's thirty-six points, a Deva-Deva pairing scores the full six, a Deva-Manushya pairing scores five, and a Deva-Rakshasa pairing scores zero, the weakest outcome the koota allows; this last rule is the one most often cited in popular accounts of the system and the one most often misread as a judgment on a person's character rather than a rule about compatibility. The word deva itself comes from a Sanskrit root meaning to shine, the same root that gives Latin deus and English divine.