ECB QE: What's It All About?

Global markets are on edge and the news channels are all talking about the expected announcement by the European Central Bank that it will start “quantitative easing,” what some people call “printing money.” Why is the ECB the last large central bank to resort to this tactic in an effort to pull the European Union out of economic stagnation, and reverse the common currency’s descent into deflation? What exactly will Mario Draghi propose in order to fulfill his promise to do “whatever it takes” to fix the EU economy, and what are the unique problems he faces that his counterparts at the Fed, Bank of England and Bank of Japan did not have?