Shamanism is a spiritual technique, where the practitioner alters his/her conscience to journey into a different reality, or, more precisely, to be able to see additional, spiritual aspects of reality. On the journey, also referred to as the shaman's flight, they consult with their spiritual guides, their power animals and teachers, to find an answer to a question.
Often, the question is asked by a person who needs help with physical or mental ailments, or to get instructions for how to deal with incidents expected to happen in the (near) future (divination.)
In addition, shamans journey about their own questions, as a method of gaining shamanic experience. One such journey would be to face one's personal greatest fear, and to learn how to overcome it.
The altered state conciseness is induced in different ways, depending on the cultures. In many societies, shamans use a very monotonous drum beat. But as often, plants are used to alter the consciousness, such fly agarics (toad stool,) peyote cacti, Ayahuasca, and even beer brewed with certain herbs, such as henbane aka stinking nightshade (German Bilsenkraut -- which is connected with the beer "Pilsner")
Many practice shamanism, but only the people of a community can name a practitioner a shaman, considering his/her life style, approaches to the universe, connection with the land and the ancestors, and success in his/her work. *)
Shamanism has been around for about 30 - 40,000 years, and can be found in all societies in the world. In some remote corners of our planet, it is still practiced as a viable part of community life. In the so called civilized world, shamanisms is either eradicated or has been taken over by religion. Nevertheless, in all world religions one can find aspects of shamanism in their scriptures and teachings.
The word itself is taken from the term the Tungusic people (from Siberia) use to refer to their practitioners. As an anthropological term, shamanism describes techniques and the basic philosophy inherent in all cultures, no matter how the people practicing this technique are actually called in their societies. For example, the Druids were the shamans of the Celtic people, even though no Celt would ever called a Druid that way. Same counts for the Holy Men/Women of the Native Americans etc.
*) Throughout the web site, I use the term shaman to describe both the shamanic practitioner and the shaman.