Final answer:
In Buddhism, the cycle of endless lifetimes of birth, death, and rebirth is known as 'samsara'. This process continues until enlightenment is achieved and the state of nirvana is reached.
Step-by-step explanation:
According to Buddhist belief, the vast network or births and deaths through endless lifetimes is called samsara. This term reflects the continuous cycle of rebirth that is influenced by one’s actions, or karma, in previous lives. The purpose of the cycle is to eventually achieve enlightenment and reach the state of nirvana, an ultimate peace characterized by the absence of desire and the end of individual suffering.