Pralaya, the Dissolution, is the Hindu cosmology, which is an era of time of the cycle of existence of the planets where activity does not occur.

The dissolution of all things is of four kinds. They are Naimittaka or occasional; Prakrittika or elemental; Atyantika or absolute and Nitya, that is perpetual.

According to Vishnu Purana, Naimittaka occurs when the sovereign of the world rests in sleep. Prakrittika or elemental is the mundane egg resolves into the primary element from whence it was derived. Atyantika is described, as the absolute non-existence of the world is the absorption of the sage through knowledge, into the supreme spirit. Lastly, Nitya signifies the perpetual destruction that is the constant disappearance, day and night, of all that are born.

In another view Naimittaka is described as the intervals of Brahma`s days. This is the destruction of creatures, though not of the substance of the world, occurring during his night.

The Prakrittika destruction occurs at the end of Brahma`s life.

The third stage, Atyantika is individual annihilation or Moksha. Moksha is the exclusion forever from future existence.

The Bhagavad Gita specifies the fourth stage Nitya or the constant dissolution to be the imperceptible change that all things suffer, in the various stages of growth and decay, life and death. The various conditions of beings subject to change are occasioned by that constant dissolution of life, which is rapidly produced by the resistless stream of time, taking everything perpetually away.

Pralaya also has another definition. According to the calculation of the Brahmas, Pralaya means 4,320,000,000 years. Manvantara, the period of activity has the same duration. Taking 360 Manvantaras and equal number of Pralayas, one `Year of Brahma` is gotten. The duration of 100 `Years of Brahma` forms a `Life of Brahma`, call of Mahamanvantara, also lasting in total 311,040,000,000,000 years. This is, according to Blavatsky, the period of activity of the cosmos, following itself a period of inactivity, Mahapralaya, of equal duration.