The Trimurti — literally “three forms” — is the classical framework through which Sanatan Dharma pictures the single, formless Brahman performing three distinct cosmic functions. Brahma creates, Vishnu preserves, and Shiva dissolves — not as three separate gods competing for authority, but as three faces of one undivided reality, each responsible for a different phase of an endlessly repeating cycle.
Brahma, the creator, is the least worshipped of the three today, precisely because his function — bringing the universe into being — is understood as already accomplished for this cycle. Vishnu, the preserver, sustains dharma through the ages, descending as an avatar whenever cosmic balance tips too far toward chaos — the ten avatars of the Dashavatara are his interventions. Shiva, the destroyer, is not a force of evil but of necessary transformation: he dissolves what has become rigid or corrupt so creation can begin again, uncorrupted.
The Trimurti is not a hierarchy but a cycle without end: creation gives way to preservation, preservation gives way to dissolution, and dissolution seeds the next creation. Later traditions often elevate one of the three as the ultimate reality of which the other two are expressions, but the underlying architecture remains the same — one being, three functions, one continuous wheel of becoming.