Vajrayāna Buddhism, also known as Tantric Buddhism, Tantrayana, Mantrayana, Mantranaya, Esoteric Buddhism, Diamond Vehicle (Cn. jingangcheng (金剛乘), Jp. kongōjō (金剛乗)) although these terms are not always regarded as equivalent , is an extension of Mahayana Buddhism consisting of differences in the adoption of additional techniques (upaya, or 'skillful means') rather than in philosophy. Thus, before terms such as Vajrayāna or Tantrayāna came into use, scholar-monks such as Buddhaguhya (fl. mid-8th CE) state that Mahāyāna is subdivided into two categories: pāramitā-yana (the "Perfection Method") and mantra-yana (the "Mantra Method"). Some of these upāya are esoteric practices which must be initiated and transmitted only through a skilled spiritual teacher. The Vajrayana is often viewed as the third major 'vehicle' (Yana) of Buddhism, alongside the Theravada and Mahayana.
