I have been curious about programming for some time, but never got down to actually starting. Now I wonder: What language would be a nice portal into general programming, just to get the idea of how languages in general work? I'm looking for a language that is easy to get into, but is powerful enough to allow me to later on create "whatever I want" or thereabout

(relax, I don't ask for The Ultimate Language). So: A language that is easy for beginners, powerful and will teach me as much as possible that I can use in other languages.
Also, are there any on-line tutorials, docs and so on on that particular language?
TiA