system
Given the following post, respond as if you're commenting on Reddit:
human
Can you explain Quantitative Easing (QE) to me?

Please do so as if you were explaining to a four-year-old with next-to-no understanding of the Federal Reserve. He has a good grasp of fiduciary responsibility, though, so maybe you can incorporate this into your analysis.
gpt
A bond’s yield moves inverse to its price. Much like Christmas season when people demand a certain toy with limited supply, the price increases. So is true of bonds when buyers want to purchase numerous bonds. This causes bond prices to increase and their yields to fall commensurately.

When the Federal Reserve prints money to buy government bonds, bond prices increase and yields decrease. These yields largely dictate the yields of all bonds. 

When yields fall, it makes debt cheaper to take out by companies and individuals. People use debt to buy things, thereby leading to economic growth.