Following the Mahaparinirvana of the Buddha, his teachings and monastic order (Sangha) underwent significant evolution. This led to the emergence of various schools or sects, each interpreting the Dharma in slightly different ways and emphasizing particular aspects of the Buddha's message. Understanding these sects is crucial for grasping the historical development and diverse philosophical landscape of Buddhism.

The initial divisions within Buddhism are often traced back to the early Buddhist councils. While the First Buddhist Council aimed to preserve the Buddha's teachings (Dhamma) and monastic rules (Vinaya), differing interpretations and the natural evolution of practices over time sowed the seeds for future divergence.

Over centuries, Buddhism broadly bifurcated into two major streams: Hinayana (Lesser Vehicle) and Mahayana (Great Vehicle). It's important to note that 'Hinayana' is a term often used by Mahayanists, and practitioners of the schools it encompasses generally prefer to be called 'Theravada' or simply refer to their specific school.

Theravada Buddhism is the oldest surviving school and is considered by many scholars to be the most conservative, adhering closely to the original teachings as preserved in the Pali Canon. It emphasizes individual liberation through the path of an Arhat. The monastic Sangha plays a central role, and the practice of Vipassanā (insight meditation) is key.

Mahayana Buddhism emerged later, around the 1st century BCE. It introduced new philosophical concepts and scriptures. The central ideal is the Bodhisattva, who vows to achieve Buddhahood for the benefit of all sentient beings. Mahayana emphasizes compassion, emptiness (Shunyata), and the concept of skillful means (Upaya) to guide beings towards enlightenment. This branch further diversified into numerous sub-schools.

Within Mahayana, several significant schools developed, each with unique philosophical emphases and practices:

Founded by Nagarjuna, Madhyamaka emphasizes the concept of Shunyata (emptiness) as the ultimate nature of reality, asserting that all phenomena are devoid of inherent existence. It seeks to refute extreme views of eternalism and nihilism.

Associated with figures like Asanga and Vasubandhu, Yogacara posits that reality is fundamentally consciousness. It explores the workings of the mind and the nature of perception, suggesting that our experience of the world is a projection of our own consciousness.

Zen emphasizes direct experience and meditation (Zazen) as the primary means to attain enlightenment, often bypassing reliance on scriptures. It values intuition and the master-disciple transmission of understanding.

This school focuses on devotion to Amitabha Buddha, believing that by chanting his name with sincere faith, one can be reborn in the Pure Land, a realm conducive to achieving enlightenment.

Often considered a branch of Mahayana, Vajrayana (prominent in Tibet, Bhutan, and parts of Japan) incorporates Mahayana philosophy but adds unique tantric practices, rituals, mantras, and visualizations to accelerate the path to enlightenment. It aims to achieve Buddhahood in a single lifetime.