After Siddhartha Gautama achieved insight into life and the nature of suffering and organized his findings into a philosophy, Buddhist thought spread from India to other countries in South and East Asia. Over the centuries, Buddhist philosophy has developed into a diverse variety of schools and are generally categorized into three main branches: Mahayana, Theravada, and Vajrayana.
Mahayana Buddhism (the Great Vehicle or the Great Raft) developed in India, China, and East Asia. With its broad and flexible approach to teaching, its incorporation of many texts, and its acknowledgement of different types of Buddhas, the Mahayana school makes Buddhism accessible to a variety of students. Mahayana Buddhism puts emphasis on helping to liberate humanity from suffering with the help of bodhisattvas, compassionate beings who delay their achievement of nirvana until all are free. Mahayana concepts became popular in the United States with the Zen Buddhist movement.
Theravada Buddhism (the Elders’ Teachings) developed in Southeast Asian countries such as Thailand, Myanmar, Laos, and Sri Lanka. Earlier scholarship referred to this branch as Hinayana (the Lesser Vehicle), but this term is seen today as pejorative. Theravada Buddhism predates Mahayana Buddhism and places more emphasis on monasticism and the transmission of knowledge through generations. Theravada Buddhists rely on an established set of Pali language texts and regard the historical Buddha as the main teacher. The ideal practitioner in Theravada is the arhat (“worthy one”), a person who has achieved Nirvana. An aspect of Theravada that has found adherents in the West is vipassana meditation.
The Vajrayana school (the Diamond Vehicle) developed in Tibet and the Himalayan region. Sometimes regarded as an offshoot of Mahayana, it joins Buddhist philosophy with the local shamanic Bön religion. Vajrayana practices include the use of rituals, mantras, and mandalas to achieve insight. Due to the incorporation of shamanic and tantric techniques, Vajrayana is also referred to the Thunderbolt school, as these methods can accelerate insight and enlightenment. Vajrayana concepts have become known in the West through the Tibetan diaspora and the lectures and publications of the current Dalai Lama.
Further Reading: Religious Literacy Project, Harvard Divinity School