The worship of Devi in Shreechakra or Sri Yantra is regarded as the highest form of worship. Originally Lord Shiva gave 64 Chakras and their Mantras to the world, to attain various spiritual and material benefits. For his consort Devi he gave the Shreechakra and the highly coveted and the most powerful Shodashakshari mantra, which is the equivalent of all the other 64 put together. It has all the Devis and Devatas. Hence if you worship this one yantra you need not worship any other yantra.
It is worshiped it in the flat plate as in the above picture and also in the Meru form. In the flat plate form the 9 Avaranas and the Bindu are represented by drawn lines and in the Meru form they are cut like a pyramid as shown in the photograph. Crystal Meru is the most common.
It is said that in the beginning God, who was one, wanted to become many and enjoy himself. As the first step to creation he created Devi – the total cosmic Female force. For the male part, out of his left he created Shiva, out of his middle he created Brahma and out of his right he created Vishnu. That is why many regard the Devi as more powerful than the Trinities and hence She is called Parashakti or Paradevi – Para meaning beyond . Brahma created the universe. Vishnu controls and runs the universe. Shiva along with Shakti is engaged in the eternal dissolution and recreation of the universe. The Bindu in the center of the Shreechakra is the symbolic representation of the cosmic spiritual union of Shiva and Shakti. Apart from that the Shreechakra also embodies countless number of deities and represents the whole of creation. Hence by worshipping the Devi in Shreechakra one is actually worshipping the highest ultimate force.