Quantitative easing explained

Quantitative easing (QE) is an unconventional monetary policy used by central banks to stimulate the national economy when conventional monetary policy has become ineffective. A central bank buys financial assets to inject a pre-determined quantity of money into the economy. This is distinguished from the more usual policy of buying or selling government bonds to keep market interest rates at a specified target value. A central bank implements quantitative easing by purchasing financial assets from banks and other private sector businesses with new electronically created money.This action increases the excess reserves of the banks, and also raises the prices of the financial assets bought, which lowers their yield.

http://en.wikipedia.org/wiki/Quantitative_easing