From what I understand, it covers a wide range of things, but essentially everyone has a "social credit score."
If you post online comments that is considered anti-government or even "read" articles and comments as such, your social credit score is lowered by certain amount of points depending on offense.
But this also records your purchase transaction. Say you buy American products in China right now during a trade war, this will lower your social credit score as well.
The more your social credit score lowers, the more restrictive things become.
For example, if you're score is only a little below say the norm, you may find yourself banned from using taxis or buses. The more score you lose, the more you are labeled dangerous to the society, you start being banned from using high speed rail and even air travel will be banned. You will not be able to leave the country etc...
It will also affect you when you go to the bank for loans or even job hunting. But of course if it gets to a certain point, you can be arrested and imprisoned.
