A school of Yog which is practiced in three stages. There are three major schools of Tantra - Kaulaa, Mishra (mixture), and Samaya. 

Kaulaa followers employ external objects as means in their spiritual practice and involve themselves in external rituals

The path of Mishra is the combination of both Kaulaa and Samaya. In fact it is the period of transition from Kaulaa to Samaya in which the followers internalize all external rituals and meditate at their heart.

Samaya is a purely Yogic path and does not rely on any external means at all. The seekers in this school perform internal worship using Praanaayaam, meditation, concentration. The seeker meditates on Sahasraar Chakra - the Crown Chakra. It is considered to be the highest of the three schools of Tantra.