YANTRA literally means "support" and "instrument". A YANTRA is a geometric design that serves as a highly efficient tool for contemplation, concentration and meditation. YANTRAS has spiritual meaning: There is a specific meaning related to higher levels of consciousness.
The Yantra offers a focus that is a window into the Absolute. When the mind is focused on a single, simple object (a yantra in this case), the mental chatter stops. Eventually, the object will be dropped when the mind can remain empty and still without help. In the most advanced stages, it is possible to achieve union with God through the geometric visualization of a YANTRA.
The YANTRA is like a microcosmic image of the MACROCOSM. It is a focal point and an outer and inner door. The YANTRAS often focus on a specific deity and such. By tuning into the various YANTRAS, you can tap into specific deities or creative power centers in the universe.
YANTRAS are usually designed with the eye carried in the center and very often they are symmetrical. They can be drawn on paper, wood, metal, or earth, or they can be three-dimensional.
The most famous YANTRA in India is the Sri YANTRA, the YANTRA of Tripura Sundari. It is a symbol of the entire cosmos, reminding the practitioner of the non-difference between subject and object.