Barack Obama has been talking about "change" since the outset of his presidential campaign. After he won the Iowa caucuses, other candidates began using the word so often it's become a mantra—not just for Democrats, but Republicans too. Are they all saying the same thing, or are they using the same word to convey different messages? Does "change" mean hope? Is it the opposite of experience? Does it mean seeing the last of George W. Bush or doing the same things, only better? Do voters want real change or a vague promise they can invest with their own expectations? We talk about the language and substance of politics.