Yantra is a pattern used in Hinduism for worship. Yantra means originally the mechanical, mnemonic and musical contraption in the macrocosm. It was a graphic symbol of the contemplative meditation of Hindu tradition which was intended to be unified with the mother goddess or Durga (not understanding). “Yang” means Anahata, so it is able to consider as the contemplative meditation relating to Anahata chakra.

                      Historically, only the part of central hexagram was emphasized later, and it became the symbolic context that expressed to be unified with Dakini in tantrism. Yantra particularly the hexagram had an influence on Vajrayana Buddhism and Western esotericism. In Vajrayana Buddhism, the hexagram came to be called Mahamudra.

                     Shapes and patterns commonly employed in yantra include squares, triangles, circles and floral patterns but may also include more complex and detailed symbols, for instance:
The lotus flower typically represents chakras, with each petal representing a psychic propensity (or vritti) associated with that chakra;
                   A dot, or bindu, represents the starting point of creation or the infinite, unexpressed cosmos;
                  The shatkona (satkona) (Sanskrit name for a Hexagram) is composed of a balance between:
                  An upwards triangle which according to Tantra denotes energy, or more specifically action and service (seva). It may also denote spiritual aspiration, the element of fire, or Shiva. It is also said to represent the static substratum of the cosmos;[citation needed]
                   A downwards triangle which according to Tantra denotes spiritual knowledge. It may also denote the creative power of the cosmos, fecundity, the element of water, or Shakti;
                   Bija mantras (usually represented as characters of Devanagari that correspond to the acoustic roots of a particular chakra or vritti).

Geometric element meanings:
Circle = Energy of the element water
Square = Energy of the element earth
Upward-facing Triangle = Energy of the element fire; energy
Downward-facing Triangle = Energy of the element water; knowledge
Diagonal line = Energy of the element air
Horizontal line = Energy of the element water
Vertical line = Energy of the element fire
Point = Energy of the element ether

Yantra as an astrological device:

                   Yantra may be used to represent the astronomical position of the planets over a given date and time. It is considered auspicious in Hindu mythology. These yantras are made up on various objects i.e. Paper, Precious stones, Metal Plates and alloys. It is believed that constantly concentrating on the representation helps to build fortunes, as planets have their peculiar gravity which governs basic emotions and karma. These yantras are often made on a particular date and time according to procedures defined in the vedas.

How do Yantra works:

                  At the basis of yantra operation is something called “shape energy” or “form energy”. The idea is that every shape emits a very specific frequency and energy pattern. Examples of old believes in shape energy are the yantras and mandalas of eastern philosophies, the star of David, the five pointed star (pentagon), the Christian cross, the pyramids and so on. Certain ‘powers’ are inscribed to the various shapes. Some have ‘evil’ or negative energies and some ‘good’ or positive energies, but in YANTRA Yoga, only the benefic and harmonious energies are used.

                        When one focuses on a yantra, his mind is automatically “tuned in” by RESONANCE into the specific form energy of that yantra. The process of RESONANCE is then maintained and amplified. The yantra acts only as a “tune in” mechanism or a doorway. The subtle energy does not come from the yantra itself, but from the MACROCOSM.

                       Basically, yantras are secret keys for establishing RESONANCE with the benefic energies of the MACROCOSM. Very often the yantras can put us in contact with extremely elevated energies and entities, being of invaluable help on the spiritual path.