What is Quantitative Easing?
Normally central banks, such as the Bank of England or US Federal Reserve, cut interest rates when they want to help the economy out.
But what about when interest rates hit rock bottom? Then they have to resort to a new, and untested, kind of policy called "quantitative easing".
The BBC's economics editor, Stephanie Flanders, explains.
You can find out more on our special report: The global economy - making it clear