A Kalpa is a vast period of time in Hindu cosmology, representing one day in the life of the creator god, Brahma. Each Kalpa lasts for about 4.32 billion years, followed by a night of equal length, during which the universe is in a state of rest. This cycle of creation and destruction is part of the larger cosmic cycle known as Kalachakra. Within a Kalpa, there are 14 Manvantaras, each ruled by a different Manu, who is a progenitor of humanity. Each Manvantara is further divided into four ages, or Yugas, which include Satya, Treta, Dvapara, and Kali. These ages represent the moral and spiritual decline of humanity over time.