I've been practicing shamanism in a dedicated way since 1996 and I've come to certain number of theories about what happens in shamanism, what shamanism is and how it works. I state very clearly that these are my theories - they're not the truth, just my opinion, based on my thinking and experience.
Shamanism is an art based on direct experience. It seems that most practitioners have the same sort of experience, but the details vary. Sometimes the details vary a lot and we end up with different systems altogether. In every case, shamanism is based upon our relationship with the Non-Ordinary Reality and Those who reside therein. In most cases shamanism takes precedent over rules and dogmas. There are some people who try to put shamanism into a cult or sect, but it doesn't go. It's by essence something free.
There are shamanic cultures though. The Evenk for instance. There we can find cultural codes and ways of doing, shared myths and customs. The Buryat have degrees of shamans and a shaman clan which takes a dominant position. Still one shaman's experience is always spirit based and what the spirits say, goes.
In the Occident, there is a revival of shamanism. Our shamanism is essentially free and personal experience based. . Shamanism is a world wide phenomena. It is present on all continents, including Europe. It has been in existence since the dawn of humanity. It will probably continue to exist, even if one day we colonize space. It exists in stone age type societies (like in Papua New Guinea) and highly technological societies (like South Korea). It is practiced by poor and rich alike, women and men alike, by all races and all age groups.
I'd define shamanism as "the art of changing one's consciousness at will, in order to go into and work in an alternative reality." What this Other Reality is, I leave open to people's own interpretations. It may be an alternative Universe, a real Spirit World, or just inside our brains. One way or the other it does exist. We go to this place, or an aspect of this place, each and every time we sleep and dream. Yes, you are a natural shamanic practitioner every time you dream.
I'd like to repeat that this is my definition of shamanism and I'm open to debate.
"Shamanism" is a valid word to describe the phenomena. There have been discussions if we should name this art shamanism or something else. The word itself comes from a culture in Siberia, and it's only one of the words they use for this art in that culture.
I personally find that if you'd stick to the theory that there is a specific worldwide phenomena where practitioners: 1) use a tool to alter consciousness at will and in a safe way 2) have part of their awareness travel into another reality 3) do work in that other reality (namely get information and/or energy and bring these elements back) 4) come back to normal reality and 5) "normal reality" has changed because of the other-worldly journey-work
... then there is a class of people on our planet who need a genuine title. We can't call them 'trancers' or 'ecstaticers' or something. The international word in use now is Shamanism.
Shamanism works with Nature, the Ancestors and Divinities
a.The work with Nature is through Nature Spirits, Natural energies and living a live in harmony with Nature.
b. The Ancestors are of course the Genetic Ancestors, but there are also Mythical Ancestors (Story Ancestors, Spiritual teachers, etc). - I may for instance have Dutch genetic ancestors, but I may be raised in a Norwegian family. In that casse I have Dutch and Norwegian ancestors. - I may have read Socrates, Plato and Epictetus. In that case these (Greek) ancestors will now become part of my philosophical ancestry. - I may have been living in France for more than half my life, especially in one region, in that case the Ancestors of that place become mine as well. These are spatial ancestors.
It's not always a question of DNA....
c. The divine is always present in our lives. It gives meaning. Monotheists shamans (those who believe in only one God) work with that God (and perhaps with the angels and saints). Polytheistic shamans may work with multiple Divinities. These divinities link us to higher goals and deeper meanings.
The first movement in shamanism is the journey inward. Before anyone ever truly leaves their body (exceptions of people reporting OBE excluded), we move inward into our Inner World. Whether our Inner World is our sub-conscious or a real extra-physical reality is something I leave open to the individual practitioner to decide.