The ultimate goal of Zen Buddhism is to attain enlightenment, also known as satori or kensho, which is a state of profound wisdom, clarity, and liberation from suffering.

Rinzai Zen, a branch of Zen Buddhism founded by the Chinese master Linji Yixuan, places great emphasis on the use of koans, which are paradoxical riddles or statements designed to challenge the intellect and lead to sudden enlightenment.

Soto Zen, another major school of Zen Buddhism, focuses on the practice of zazen, which is a form of seated meditation aimed at cultivating mindfulness, concentration, and insight.

Bodhidharma, an Indian monk who traveled to China in the 5th century CE, is traditionally regarded as the founder of Zen Buddhism. He is credited with introducing the practice of zazen and koans to China, which later spread to Japan and other parts of East Asia.

The term 'Zen' is derived from the Chinese word 'chan', which in turn is derived from the Sanskrit word 'dhyana', meaning 'meditation'. Zen Buddhism emphasizes the practice of meditation as a means to achieve enlightenment and liberation from suffering.

The Platform Sutra, also known as the 'Platform Scripture', is a collection of teachings attributed to the Chinese Zen master Huineng. It is considered one of the most important texts in Zen Buddhism and is often referred to as the 'Bible of Zen'.

The concept of 'mu' in Zen Buddhism refers to emptiness or nothingness. It is often used to describe the true nature of reality, which is beyond conceptualization and duality. The koan 'What is the sound of one hand clapping?' is an example of a mu koan, designed to lead the practitioner to an understanding of emptiness.

Dogen Zenji, the founder of the Soto Zen school in Japan, developed a 'five ranks' system of enlightenment, which describes the progressive stages of spiritual development leading to full enlightenment. These ranks include the ranks of beginner, progressing, seeing into one's nature, realizing one's nature, and attaining buddhahood.

The bodhisattva ideal is central to Zen Buddhism. A bodhisattva is a being who has attained enlightenment but chooses to remain in the world to help others achieve enlightenment as well. This selfless aspiration to help others is considered a manifestation of compassion and wisdom.

Kinrin is a Zen Buddhist practice that involves the use of a wooden stick or staff. It is used by Zen masters to strike students during meditation or koan introspection sessions. The purpose of kinrin is to break through mental barriers, promote mindfulness, and encourage the student's progress on the path to enlightenment.

Sangha is the traditional form of Zen Buddhist monastic community. It consists of a group of monks or nuns who live together, practice Zen meditation, and study the teachings of the Buddha. The sangha provides a supportive environment for spiritual growth and development.

Sesshin is a Zen Buddhist ritual that involves a week-long intensive meditation retreat. During sesshin, participants engage in long periods of zazen, koan introspection, and other meditative practices. Sesshin is a time for deep spiritual introspection and self-discovery.

The lotus flower holds a significant place in Zen Buddhism. It represents purity and detachment, as it grows in muddy waters but remains unstained. It also symbolizes enlightenment and wisdom, as it emerges from the mud and blooms beautifully. Additionally, the lotus flower is associated with the bodhisattva Avalokiteshvara, who is known for his compassion and mercy.

Hakuin Ekaku, a prominent Zen master of the Rinzai school, is known for his 'three pillars of Zen': seeing into one's own nature, breaking through the great doubt, and attaining full enlightenment. These three pillars represent the essential stages of the Zen path and are considered fundamental to achieving enlightenment.

The concept of 'beginner's mind' in Zen Buddhism refers to an open and receptive attitude, free from preconceptions and assumptions. It is a state of mind that is willing to learn, explore, and experience the world with a fresh perspective. Beginner's mind is considered essential for spiritual growth and development.