Buddhism
Founded by Siddhartha Gautama (the Buddha) ~5th century BCE in India. Four Noble Truths and the Eightfold Path to end suffering (dukkha). ~500 million adherents worldwide.
Sub-topics
The 'School of the Elders' — oldest surviving Buddhist school, ~3rd century BCE. Pali Canon as authoritative text. Emphasis on individual enlightenment (arahant). Dominant in Sri Lanka, Thailand, Myanmar, Cambodia, Laos.
The 'Great Vehicle' — emerged ~1st century CE. Bodhisattva ideal: delay your own enlightenment to help all sentient beings. Expanded canon with new sutras. Dominant in East Asia.
The 'Diamond Vehicle' — esoteric Buddhism emphasizing tantric practices, mantras, mudras, mandalas, and guru-disciple transmission. Emerged ~7th century CE in India, flourished in Tibet and Mongolia.