An ascetic Tibetan Buddhist sect. The Kagyu, Kagyü, or Kagyud (Tibetan: བཀའ་བརྒྱུད, Wylie: bka' brgyud) school, also known as the "Oral Lineage" or Whispered Transmission school, is today regarded as one of six main schools (chos lugs) of Himalayan or Tibetan Buddhism, the other five being the Nyingma, Sakya, Jonang, Gelug and Bon. Along with the Sakya and Gelug schools, the Kagyu tradition is classified as one of the Sarma or "New Transmission" schools of Vajrayāna founded during the second diffusion of Buddhism into Tibet (diffusing the so-called "New Tantras"). It is a Red Hat sect along with the Nyingma and Sakya.
Due to the Kagyu tradition's particularly strong emphasis on guru devotion and guru yoga, and the personal transmission of esoteric instructions (Wylie: dam ngag or man ngag) from master to disciple, the early Kagyu tradition soon gave rise to a bewildering number of independent sub-schools or sub-sects centered on individual charismatic Kagyu teachers and their lineages. These lineages are hereditary as well as mindstream emanation in nature.