Four forms of
pralayas
or dissolution
are enumerated in the Vedas.
Nitya Pralaya
Every night, when we fall into a deep sleep, our consciousness goes through dissolution daily.
Naimittik Pralaya
 At the end of Brahma’s day, all the abodes up to the
Mahar Lok
dissolute, and all the souls residing there become unmanifest. They remain in a state of suspended animation in the body of Vishnu, waiting for the next cycle of creation. When Brahma creates these
lokas
again, these souls are reborn based on their past karmas.
Mahā Pralaya
 At the end of Brahma’s life, this entire universe goes into dissolution. Again, all the souls of the universe unmanifest and stay in the body of Maha Vishnu. Their gross (
sthūl
) and subtle (
sūkṣhma
) body dissolve, but their causal body (
kāraṇ sharīr)
stays. In the next cycle of creation, these souls are reborn based on their past karmas and past
sanskārs,
which the soul’s causal body stores and carries with it.
Ātyantik Pralaya
 This is the dissolution from the clutches of maya that has been binding the soul since eternity. It takes place when the soul finally attains God and is liberated forever from the cycle of birth and death.