Taliban. Who are they?

Last week I have witnessed the conference on Afghanistan. Till this days I had idea that I know who are that guys who are popular to world as Taliban. But in that conference took part fellows with the most deep information (among the humankind) about them. At the end of discussion I came to a conclusion that we don't know who are the Taliban, what is this, and how they are operating. They say Taliban are ordinary afghan guys,

but others said they not peaceful.


Some of them says that they pushtuns, but one guy from Afghanistan said that they are NOT pushtuns. And so on...
Is there anybody among the people who knows who are the Taliban?