Etymologically trinity means three-in-one, where three entities create a universal totality. In Hindu Dharma, the existence of three Gods, Bramha, Vishnu, and Shiva forms the Trinity where God Bramha is the creator, Vishnu is the cosmic lord, and Shiva is believed to be the terminator who destroys for complete regeneration from the way of destruction, and thus the cycle of creation and destruction runs on and on.
This Trinity is also termed as Sat-Tat-Aum. The perception of trinity also supports the conception of One-God-One-Universe theory where the creator, preserver, and the terminator get mingled with each other.
Each of the entities has their companions like Bramha has Saraswati with him, while Shiva has Kali and Vishnu is accompanied by Lakhmi. Surprisingly, these female consorts are perfectly matching the role of their male counterparts like Saraswati is believed to be the goddess of wisedom, Laskmi is the goddess of love, prettiness and delight, and Kali is the goddess of power, annihilation and renovation.
According to Hindu Cosmology concept Bishnu remains in slumber in between a cosmic cycle in the ocean called Garbhodaka Ocean. It’s a cosmic slumber induced by Yoganidra. One cosmic cycle is set in motion when a lotus with one thousand petals springs out of the navel of Lord Bishnu. In the middle of the lotus remains Brahma, the Holy creator. Brahma looks around at four directions and observes the cosmic ocean, and initiates the rolling stone of creation. When His creation gets over, Vishnu maintains it. He does this principally through the dictum of dharma, the religion based on the Hindu perception of truth and virtue. At the end of the cycle Shiva destroyes everything and again Bramha starts His creation. These Trinity rules and manages Universe and that is why they are eternal at one point…the power is supreme called “the Almighty”.