Yantra literally means loom, instrument or machine. In actual practice, a yantra is a symbolic representation of aspects of divinity. It is an interlocking matrix of geometric figures, circles, triangles and floral patterns that form fractal patterns of elegance and beauty. Yantras function as revelatory symbols of cosmic truths; furthermore, they are said to represent a map of both the universe and an individual's mind or consciousness. Practitioners often use a yantra and a mantra representing the same aspect of the Divine together. 

Significance of yantras in Vedic astrology

    According to Vedic Shastras, yantra is a science which can be used through the five elements-earth, water, fire, sky and air and by recitation of mantras to control nature in one's own interest. Deities are worshiped in different forms and each form is linked to a yantra. Yantra uses signs and writings to remove a planet's malice effects and increase it's beneficial aspects