A yantra is a sacred geometric diagram used in tantric and Vedic traditions as a focus for meditation, ritual worship, and as a remedial measure. It is considered the visual form of a deity or a cosmic principle — analogous to a mantra (sound form) or a murti (physical form). The Sri Yantra (nine interlocking triangles representing Shakti) is the most revered. Planetary yantras (Surya, Chandra, Mangala yantras, etc.) are used in Jyotish as astrological remedies — specific geometric patterns associated with each of the nine grahas, typically inscribed on metal plates, paper, or carved in stone. Yantras are consecrated through specific rituals before use.