system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What does it mean when the US accuses China of "manipulating its currency"
gpt
One of the reasons everything is made in China is because it is cheap.  One of the reasons it is cheap is because China has a lot of people that need jobs so they accept low wages because the alternative is to have no job at all and starve.

As Chinese people start working they begin to earn money and want to buy things like cars and apartments and have families.  This means they need more money and they start to demand higher wages.  Higher wages mean things cost more and pretty soon making stuff in other countries makes more sense.

So China takes in all this cash from making iPods or whatever and this would normally cause the value of the Yuan to rise (again, making things more expensive).  So the Chinese print more Yuan at their treasuries and they buy things like US T-Bills.  The more Yuan there are on the market the less each one is worth to the rest of the world.

Therefore things stay cheap and China can keep people employed and not starving in the streets.