Pralaya, in Hindu cosmology, is an aeonic term for Dissolution, which specifies different periods of time during which non activity situation persists, as per different formats or contexts. The word Mahapralaya stands for Great Dissolution. During each pralaya, the lower ten realms (loka) are destroyed, while the higher four realms, including Satya-loka, Tapa-loka, Jana-loka, and Mahar-loka are preserved. During each Mahapralaya, all 14 realms are destroyed.
In the Samkhya philosophy, one of the six schools of classical Indian philosophy, Pralaya means "non-existence, a state of matter achieved when the three gunas (principles of matter) are in perfect balance. The word pra-laya comes from Sanskrit meaning 'dissolution' or by extension 'reabsorption, destruction, annihilation or death'.
Praakritik Pralaya, which is of 311,040,000,000,000 solar years duration, occurs after the completion of life of Brahma (i.e. 100 Brahma years = 311 trillion and 40 billion earth years = one day of Vishnu = 1 Parama). After the completion of one Brahma life cycle, the complete dissolution of all the entities (i.e. the Pancha Mahabhutha or Universe) takes place in the eternity (God). Praakritik Pralaya is the time for which Vishnu sleeps. The next morning, he again gives birth to a new Lord Brahma and asks him to create new worldly entities. Noticeably, Praakritik Pralaya and the Life of Brahma are of equal duration.
Naimittika Pralaya, which is of 4,320,000,000 earth years, occurs just after the end of a Kalpa. Also, known as the Night of Brahma, it signifies the end of living world. In Bhagvata Purana, sage Shukdeva told king Parikshit that if Lord Brahma is supposed to be a child (for example), then in a similar way as a child plays with his toys i.e. making various structures from his toys during day and breaking or dismantling them before he goes to sleep at night; Brahma makes the living world during his day (i.e. Kalpa) and destroys it before going to sleep during night (i.e. Naimittika Pralaya). A new living world is created by Brahma, when he wakes up the next day and so on the cycle continues till Praakritik Pralaya. Again, Naimittika Pralaya and Kalpa are of equal duration.
Atyantik Pralaya, also termed as Moksha, is the final deliverance or the attainment of salvation by a jivan (soul) and after that the jivan is never again in the clutches of karma; nor bounded by the tight ropes of Samsara. It is therefore a variable time span conditioned or determined by the practise of the different kind of Yogas or Prapatti. It is the final immersion of a soul (i.e. atma), thereby completely eliminating its individualism into the eternal almighty (i.e. Paramatma).
Nitya Pralaya, is the sleep or by an extension thereof, Death.
Pralaya in popular culture
"Pralaya" appears in the Persona series of games (specifically Persona 3 and Persona 4) as an attack. While it can be inherited to other Personae, its original user is "Shiva", a Persona based on the Hindu deity of the same name.