The Vajrayana (Sanskrit: lit. The Adamantine Vehicle) school of Buddhism, practiced predominantly in Tibet, Mongolia and Bhutan, consists of a collection of techniques for the practice of Mahayana, along with the texts that expound those techniques (the Tantras). It is also known to the west as Tantric Buddhism. Being the foundation for Buddhism, it is sometimes expounded as a third and separate major school of Buddhism, alongside the Mahayana and Theravada.

There are four main schools of Tibetan Buddhism: Nyingma, Sakya, Kagyu, and Geluk. All four schools identify themselves as belonging to the Mahayana or "Great Vehicle" tradition, which dominates in China, Korea and Japan. Vajrayana Buddhism also went to China where it flourished only briefly, and to Japan where Kukai founded the Shingon school.

• The techniques are characterized by:
  • The use of mantras, or short verbal formulae
  • Strong focus on the guru, or teacher
  • A highly-developed tradition of meditation, including concentration techniques such as the visualization of bodhisattvas.

These can be divided into four categories, namely,

• Kriyayoga
• Charyayoga
• Yogatantra
• Anuttarayogatantra, which is furthermore divided into "mother", "father" and "non-dual" tantras.

• Three Outer Tantras:
  • Kriyayoga
  • Charyayoga
  • Yogatantra
• Three Inner Tantras, which correspond to the Anuttarayogatantra:
  • Mahayoga
  • Anuyoga
  • Atiyoga - Dzogchen

Vajrayana, which developed in Northern India circa 7th century, has its main philosophical roots in Madhyamika of Nagarjuna, Chandrakirti and Vijnanavada (aka Yogachara), Chittamatra) of Asanga, and Vasubhandu. Padmasambhava is the most famous teacher of Vajrayana in Tibet, and in Japan it is Kukai.