The most important belief in Buddhism is that afterlife exists and not everything ends with death (Buddhist principles of karma and rebirth).
The reincarnation, people are reborn after dying, is one fundamental belief of Buddhism. After many cycles, if a person releases their attachment to desire and the self, they can attain Nirvana (a state of liberation/freedom from suffering).
The Buddhist path to Nirvana: To lead a moral life; To be mindful and aware of thoughts and actions; To develop wisdom and understanding.
Buddhism is a religion and a “philosophy”. It has its origins about 2,500 years ago when Siddhartha Gotama (the Buddha), was himself enlightened at the age of 35.