Another newb question (was in the wrong forum before repost)

I keep reading that actionscript is “so powerful” and how “you can do anything” with actionscript. My question is what are some examples of powerful apps you can build with actionscript? I’m vaguely aware, or at least I think that, if you wanted to create a program like microsoft outlook for example, you could learn c and then build it… I think maybe you could even use visualbasic- is that correct? So can one build applications to the likes of outlook using actionscript? If so, why would one chose to build an app with actionscript, as opposed to visualbasic or c or another language? (lol sorry for the long question)