The Trikāya doctrine (Sanskrit, literally "three bodies"; Chinese: 三身; pinyin: sānshēn; Japanese pronunciation: sanjin, sanshin; Korean pronunciation: samsin; Vietnamese: tam thân, Tibetan: སྐུ་གསུམ, Wylie: sku gsum) is a Mahayana Buddhist teaching on both the nature of reality and the nature of Buddhahood.
Even before the Buddha's parinirvāṇa, the term Dhammakāya was current. Dhammakāya literally means Truth body.
In the Pāli Canon, Gautama Buddha tells Vasettha that the Tathāgata (the Buddha) is the Dhammakāya, the 'Truth-body' or the 'Embodiment of Truth', as well as Dhammabhūta, 'Truth-become', 'One who has become Truth.' 
The Buddha is equated with the Dhamma: "[T]he Buddha comforts him, 'Enough, Vakkali. Why do you want to see this filthy body? Whoever sees the Dhamma sees me; whoever sees me sees the Dhamma.'"
In the Aggañña Sutta, the Buddha advises Vasettha that whoever has strong, deep-rooted, and established belief in the Tathagata can declare that he is the child of Bhagavan, born from the mouth of Dhamma, created from Dhamma, and the heir of Dhamma. Because the titles of the Tathagatha are: The Body of Dhamma, The Body of Brahma, the Manifestation of Dhamma, and the Manifestation of Brahma.
Mahayana Buddhism introduced the Sambhogakāya, which conceptually fits between the Nirmāṇakāya (the manifestations of enlightenment in the physical world)[note 1] and the Dharmakaya. The Sambhogakaya is that aspect of the Buddha, or the Dharma, that one meets in visions and in deep meditation. It could be considered an interface with the Dharmakaya.
Around 300 CE, the Yogacara school systematized the prevalent ideas on the nature of the Buddha in the Trikaya or three-body doctrine.
As with earlier Buddhist thought, all three forms of the Buddha teach the same Dharma, but take on different forms to expound the truth.
According to Schloegl, in the Zhenzhou Linji Huizhao Chansi Yulu, the Three Bodies of the Buddha are not taken as absolute. They would be "mental configurations" that "are merely names or props" and would only perform a role of light and shadow of the mind.[note 2]
Do you wish to be not different from the Buddhas and patriarchs? Then just do not look for anything outside. The pure light of your own heart [i.e., 心, mind] at this instant is the Dharmakaya Buddha in your own house. The non-differentiating light of your heart at this instant is the Sambhogakaya Buddha in your own house. The non-discriminating light of your own heart at this instant is the Nirmanakaya Buddha in your own house. This trinity of the Buddha's body is none other than here before your eyes, listening to my expounding the Dharma.
Vajrayana sometimes refers to a fourth body called the svābhāvikakāya (Tibetan: ངོ་བོ་ཉིད་ཀྱི་སྐུ, Wylie: ngo bo nyid kyi sku) "essential body", and to a fifth body, called the mahāsūkhakāya (Wylie: bde ba chen po'i sku, "great bliss body"). The svābhāvikakāya is simply the unity or non-separateness of the three kayas.
In dzogchen teachings, "dharmakaya" means the buddha-nature's absence of self-nature, that is, its emptiness of a conceptualizable essence, its cognizance or clarity is the sambhogakaya, and the fact that its capacity is 'suffused with self-existing awareness' is the nirmanakaya.
The interpretation in Mahamudra is similar: When the mahamudra practices come to fruition, one sees that the mind and all phenomena are fundamentally empty of any identity; this emptiness is called dharmakāya. One perceives that the essence of mind is empty, but that it also has a potentiality that takes the form of luminosity.[clarification needed] In Mahamudra thought, Sambhogakāya is understood to be this luminosity. Nirmanakāya is understood to be the powerful force with which the potentiality affects living beings.
In the view of Anuyoga, the Mind Stream (Sanskrit: citta santana) is the 'continuity' (Sanskrit: santana; Wylie: rgyud) that links the Trikaya. The Trikāya, as a triune, is symbolised by the Gankyil.
A ḍākinī (Tibetan: མཁའ་འགྲོ་[མ་], Wylie: mkha' 'gro [ma] khandro[ma]) is a tantric deity described as a female embodiment of enlightened energy. The Sanskrit term is likely related to the term for drumming, while the Tibetan term means "sky goer" and may have originated in the Sanskrit khecara, a term from the Cakrasaṃvara Tantra.
Ḍākinīs can also be classified according to the trikāya theory. The dharmakāya ḍākinī, which is Samantabhadrī, represents the dharmadhatu where all phenomena appear. The sambhogakāya ḍākinī are the yidams used as meditational deities for tantric practice. The nirmanakaya ḍākinīs are human women born with special potentialities; these are realized yogini, the consorts of the gurus, or even all women in general as they may be classified into the families of the Five Tathagatas.
Theosophy, a Western esoteric school founded in the 19th century, regards Buddhism as containing esoteric teachings. In those supposed esoteric teachings of Buddhism, "exoteric Buddhism" believes that Nirmanakaya simply means the physical body of Buddha. According to the esoteric interpretation, when the Buddha dies, he assumes the Nirmanakaya instead of going into Nirvana. He remains in that glorious body he has woven for himself, invisible to uninitiated mankind, to watch over and protect it.