The Buddha was born as the prince Siddhartha Gautama in the Kingdom of Sakyas in Nepal around 560 BC and was protected from seeing or knowing of suffering of the people in his kingdom throughout his early years. After discovering the truth, he devoted his life to the end of suffering. After six years of searching, studying with various gurus, fasting, meditating and devotion to finding the truth, he finally gained enlightenment while meditating under a Bodhi Tree (tree of awakening) and was then known as the Buddha (the awakened or enlightened one).
Upon his enlightenment, the Buddha spent 45 years teaching how to achieve liberation from suffering through practice of righteousness (dharma) and principles of living each life on earth (karma) which would eventually lead to the state of nirvana, a perfect state of peace and enlightenment.
Dharma is broken down into the Four Noble Truths.
Suffering is caused by selfish desires and attachments, and the way of overcoming suffering is by following the middle way, or the Noble Eightfold Path.
Karma is the cause and effect of good or bad thoughts and actions of previous lives on earth.
Reincarnation is the rebirth cycle on the earthly (carnal) plane of existence. It continues until the karma cycle is broken through right thoughts and actions, eventually leading to the state of enlightenment. Persons who have incarnated many times are referred to as old souls.
Three Characteristics of Existence
Factors of Enlightenment