Ishtadevatas (Yidams):

In Buddhism, Yidams are fully enlightened beings who are the focus of personal meditation during a retreat or for one's life. A Yidam is an enlightened being who one identifies with during meditation: One perceives his or her own Buddha nature through such identification. Some common Yidams include Hayagriva, Vajrakilaya, Samputa, Guhyasamaja, Yamantaka, Hevajra, Kurukulle, Cakrasamvara, Vajrayogini, and Kalacakra. Also, other enlightened beings such as the regular forms of the Buddhas, Bodhisattvas, Guru Rinpoche, certain Dharma Protectors & Wealth Deities, etc., can also be practiced as a Yidam. Yidams are not to be equated with patron saints or guardian angels found in the Jewish, Christian and Muslim traditions. They are not regarded as protectors from danger or saviors. They are simply acknowledgments of the student’s basic energy. The student visualizes the outstanding characteristics of the yidam until he achieves complete union with him. The Yidam, which can be masculine or feminine, may refer to the personnal deity, the nature of which corresponds to the individual psychological temper of each adept.

Chenrezi, Tara under her different forms, Manjusrhi and pecularly Kalachakra, Hevajra and consort Nairatmya, Heruka and consort Vajravarahi, etc are frequently chosen as Yidam, but each deity of the tantric pantheon may be adopted as such. The adept enters in union with his Yidam from the morning onwards, and ends theday with him. The Yidam is used as a means of transformation. According to certain traditions, the Yidam are considered as the emanation of the adepts own spirit.

Yab-yum deities:

A variation of the Yidam, these esoteric iconographies often found in Hindu and Tantric Buddhism. Yab-yum is generally understood to represent the mystical union of the method (upaya - conceived of as masculine) with wisdom (prajna - conceived of as feminie) - a fusion necessary to overcome the false duality of object and subject. So therefore it has nothing to with tantric sex or sacred sex as written in the Hindus texts, such as Kama Sutra (Treatise on Passion). The representation of deities in sexual union with their feminine double is called YAB-YUM, tibetan word which can be translated as "Father-Mother". This representation is very frequent in tibetan buddhism (Vajrayana) pecularly concerning the tutelary deities, and symbolizes very precisely the union of Wisdom and Compassion Strengthes. This notion is not the same in buddhism and in hinduism. In hinduism, this "embraced posture" represents the divine strength of creation.

The hindu concept is the one of a passive masculine deity, embracing his spouse called shakti, which represents his activity or power.

In buddhism, the masculine form is active, it represents compassion and skilful means (which have to be developped in order to reach Enlightenment). The feminine form is passive and represents wisdom, necessary to Enlightenment, it is the awakening to the consciousness of universal vacuity. The same ideas are to be found concerning the bell and the dorje, which, like the Yab-Yum, symbolize the dualism which must be exceeded.

Wether they are worked in the shape of statues, or painted on tangka, the YAB-YUM forms (Father-Mother) are used as a means for concentration in order to reach the fusion through the "Sadhana" of the masculine and feminine energies of the meditating person.