Article: In Theravada Buddhism, the ultimate goal is the attainment of the sublime state of Nirvana, achieved by practicing the Noble Eightfold Path (also known as the Middle Way), thus escaping what is seen as a cycle of suffering and rebirth. Mahayana Buddhism instead aspires to Buddhahood via the bodhisattva path, a state wherein one remains in this cycle to help other beings reach awakening. Tibetan Buddhism aspires to Buddhahood or rainbow body.

Now answer this question: How is Nirvana achieved?
practicing the Noble Eightfold Path (also known as the Middle Way)