The Taliban is another form of an Ultra Fundamentalist Religious organization. The equivalent in the west is the Far right Fundamentalist Christian movement. Or the Fundamentalist Jewish ultraorthodox movement.
Specifically the Taliban is an offshoot of the Sunni sect. However they HATE any other Islamic people who argue their specific branch of Islam. Heck, they hate anyone else!
Often you hear people (even here on ASK) who make a statement like: The only true Christians are Roman Catholics. (As if Catholicism is the only Religion that follows Jesus as it's core) The Taliban feel 'they' are Islam's only true followers. But, they will KILL you for disagreeing with them.
After many conversations (both on ASK and with live people) It has become apparent to me that the reason why even moderate, peaceful Muslims won't publicly decry the Taliban/Al-queda movement is they are worried that they will be killed for speaking out against the radicals.