There was a very interesting story about the teaching of Zen regarding wisdom, which was started with a thief. I hope that you will follow the link to learn more (http://www.zenguide.com/).

Zen Buddhism: Zen refers to meditation. Zen teaches how the soul is enlightenment. Zen Buddhism focuses on attaining enlightenment through meditation as the mentor Siddharta Gautama did. Zen teaching is achieved through the realization of personal well being. Teaching in awakening of a person can be achieved gradually by ones own efforts or in a flash of insight (as emphasized by the Soto and Rinzai schools, respectively).

Reading scriptures and deities in Zen Buddhism may help a little. Most preferred subjects are patriarchs, teachers, and enlightened individuals. In Zen Buddhism, the two terms “wabi and sabi” is very important. It means simplicity of the natural world and distinctive aesthetic feelings. These two amorphous concepts are used to express a sense of rusticity, melancholy, loneliness, naturalness. One term pleases the senses, and the other stimulates the mind and emotions. Training and learning in the Zen Buddhism is usually undertaken by a disciple under the guidance of a master (mentor).

Zen is also the well-known school of Buddhism in America, Japan, China, Bangladesh, India, Europe, etc. There are approximately 9.6 million Zen Buddhists in Japan, and different Zen groups have been developing.

Soto Buddhism is another Zen sect that was transmitted from China to Japan. It emphasizes zazen, or sitting meditation, as the means to attain enlightenment.

http://www.metmuseum.org/toah/hd/zen/hd_zen.htm
http://www.religionfacts.com/buddhism/sects/zen.htm

Zen is perhaps the most well-known school of Buddhism in America. Its concepts have been influential on western society since the latter half of the 20th century. There are about 9.6 million Zen Buddhists in Japan today, and numerous Zen groups have developed in North America and Europe within the last century.

Zen Beliefs and Practices
Both the words "Zen" (Japanese) and "Ch'an" (Chinese) derive from the Sanskrit word Dhyana, meaning "meditation." Zen Buddhism focuses on attaining enlightenment (bodhi) through meditation as Siddharta Gautama did. It teaches that all human beings have the Buddha-nature, or the potential to attain enlightenment, within them, but the Buddha-nature been clouded by ignorance. To overcome this ignorance, Zen rejects the study of scriptures, religious rites, devotional practices, and good works in favor of meditation leading to a sudden breakthrough of insight and awareness of ultimate reality. Training in the Zen path is usually undertaken by a disciple under the guidance of a master.

Zen in China
Zen began in China (where it is called Ch'an) in the 6th century CE. Its introduction to China is generally attributed to Bodhidharma, a South Indian monk who arrived in China in about 520 CE. Its philosophical background can be found in the Lankavatara Sutra, which was composed in the 4th century or earlier in India. As it developed in China, it was also influenced by Taoist concepts. This is especially apparent in the Ch'an emphasis on spontaneity and naturalness in all things, which significantly influenced Chinese painting, writing, and other arts.

Zen in Japan
Zen Buddhism arrived in Japan as early as the 7th century, but did not develop significantly there until the 12th century. Zen has since been an important force in Japan. It has had considerable influence on Japanese culture, "reaching far beyond the temple and entering into cultural and social areas of all kinds, including gardening, ink painting, calligraphy, the tea ceremony, and even military strategies. " {2} Zen priests played an important role in the political unrest of 16th century Japan, both serving as diplomats and administrators and preserving Japanese cultural life.

Schools within Zen Buddhism
Several schools of Zen developed in China in the 9th century. The Rinzai (Chinese, Lin-chi) sect of Zen was introduced to Japan by the Chinese priest Ensai in 1191. Rinzai Buddhism emphasizes the use of koans, paradoxical puzzles or questions that help the practitioner to overcome the normal boundaries of logic. Koans are often accompanied by shouts or slaps from the master, intended to provoke anxiety leading to instant realization of the truth. Unlike the Ch'an schools in China, Ensai also taught that Zen should defend the state and could offer prayers and incantations. "These teachings influenced the warrior class and led to a Zen influence over the martial arts of archery and swordsmanship." {3}

Soto Buddhism (Chinese, Ts'ao-tung) is another Zen sect that was transmitted from China to Japan. It arrived in Japan in 1227 upon the teacher Dogen's return from China. Soto emphasizes zazen, or sitting meditation, as the means to attain enlightenment. The Soto practitioner is encouraged to clear the mind of all thoughts and concepts, without making any effort towards enlightenment, until enlightenment occurs.

References
"Zen." Encyclopædia Britannica (Encyclopædia Britannica Premium Service, 2004).
Rutherford, Scott (ed.) East Asia. London: Apa Publications (1998); pg. 285.
"Buddhism: Mahayana: Dhyana (Ch'an/Zen)," Encyclopedia Britannica Premium Service (2004).
More Zen Resources
Manual of Zen Buddhism - Internet Sacred Text Archive
Complete text of Daisetz Suzuki's 1935 masterwork, including Shubun's ten oxherding pictures (15th century).
Soto School Scriptures for Daily Services and Practice
Text of sutras & dharanis regularly chanted by Soto Zen monks (posted by Stanford Center for Buddhist Studies ).
Zen Buddhism - World Civilizations
Brief introduction to basics of Zen.
Zen Tails Children's Books
Charmingly illustrated e-books teaching Zen principles. Free to download.

according to the wikipedia the world "Zen" is a school of Mahāyāna Buddhism. So I think it is a school of Buddhism.

hey! Zen is a school of Mahāyāna Buddhism, translated from the Chinese word 禅 Chán to Japanese. This word is in turn derived from the Sanskrit dhyāna, which means "meditation" Zen emphasizes experiential prajñā, particularly as realized in the form of meditation, in the attainment of enlightenment. As such, it de-emphasizes theoretical knowledge in favor of direct, experiential realization through meditation and dharma practice.
The establishment of Zen is traditionally credited to be in China, the Shaolin Temple, by the South Indian Pallava prince-turned-monk Bodhidharma, who came to China to teach a "special transmission outside scriptures" which "did not stand upon words". The emergence of Zen as a distinct school of Buddhism was first documented in China in the 7th century AD. It is thought to have developed as an amalgam of various currents in Mahāyāna Buddhist thought—among them the Yogācāra and Mādhyamaka philosophies and the Prajñāpāramitā literature—and of local traditions in China, particularly Taoism and Huáyán Buddhism. From China Zen subsequently spread south to Vietnam, and east to Korea and Japan.