Four classes of tantra

Four classes of tantra — the Sarma tradition of new translation schools, recognizes four classes of tantra:

Three outer classes—

• Kriya Tantra,
• Charya Tantra and
• Yoga Tantra, and

One inner class of tantra, which is called

• Anuttarayoga Tantra, or Highest Yoga Tantra.

The latter is divided into three:

• father tantras, such as the Guhyasamaja, the King of Tantras;
• mother tantras, such as Heruka Chakrasamvara; and
• non-dual tantras, such as Kalachakra.

See also six classes of tantra, of the Nyigma school.