Maha Shivratri, the “Great Night of Śiva,” is observed on the Krishna Paksha Chaturdashi—the fourteenth lunar night—known as Phālguna in the North Indian reckoning and Māgha in the South Indian reckoning (the observance is the same day).
Spiritually, the night is an invitation to jāgaraṇa—wakeful inwardness—where silence becomes a form of worship: Śiva as the still, luminous awareness within, and Śakti as the living power of transformation. Devotees traditionally keep a fast, offer bilva leaves and white flowers, and perform abhisheka—ritual bathing of the liṅga—while chanting Shiva mantras through the night.
The principal pūjā is often timed around Niśītā Kāla (midnight), though exact windows vary by location; many calendars provide city-specific timings.