Shiva and Shakti are the basics of Tantra philosophy. The essence of Shiva and Shakti are undifferentiated unity. They cannot be separated.
Shiva is represented as the unmanifest, formless, consciousness and Shakti the manifested formed, energy not only in the cosmic sense, but also in each and every individual. Everything that exists has consciousness and manifestations, and every manifestation has consciousness within it. In Tantra this consciousness is called Shiva and its manifestation is called Shakti. So in the ultimate sense they are one and the same.
The union of Shiva and Shakti is the supreme experience. This has different name in different groups. Some call it nirvana, samadhi, oneness or para, Bindu, Brahma. Para, Bindu can be considered as a point in which everything that has the potential to be expressed is contained.. It contains three qualities so it ialso called sugana Bindu.
This Para Bindu creates three Gunas- sattwa, raja and tama, it becomes Tri Bindu. This Tri Bindu Shakti that encloses a space is in the form of a triangle with the apex pointing downwards. It is also said Shakti has three eyes which are symbolized by sun, moon and fire. These sun, moon and fire represent the three nadis in the spine: Ida, Pingala and Sushumna respectively. And this triangle is also called the body of Shakti - knowledge power, action power and will power the three necessary qualities of creation.
Sattwa: Sattva is the state of purity, wisdom and harmony and equilibrium between consciousness and energy, purusha and prakriti, Maha Shiva and Maha Shakti.
Raja: Raja is the state of desire, movement and it is maya shakti, the dynamic aspect of shiva, consciousness which continuously creates different forms.
Tama: Tama is ignorance, inertia and slowness and it is maya shiva, consciousness stripped of its power and veiled by the action of maya shakti.