system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is the printing of currency regulated? When do they print more/less than previously ?

title :)
gpt
Central Banks (like the Federal Reserve in the US, or the ECB in Europe) have the responsibility to manage the amount of currency in their respective countries.

The 'how' is quite interesting: by now, most money is digital. It's one's and zero's in a computer, and doesn't exist as coins or pieces of paper anymore. So when a central bank wants to create money, they can just create it on a computer without ever needing to print anything. When they want that money in circulation, they just spend the money. Usually they buy government bonds, sometimes other bonds or stocks. These things keep their value pretty well, so if the central bank wants to decrease the amount of money in circulation, they can simply sell the bonds and/or stock, and destroy the money they get for this (again, they do this just on the computer).

The "when" is a little trickier. The Federal Reserve has what is known as a dual mandate. This means they're supposed to take care of two things: full employment (in practice this means just very low unemployment, you're never going to have no unemployment), and stable prices (in practice this means 2% inflation per year). But the thing to keep an eye on, is that central banks are not so much reacting to what's already happened, but they're trying to predict what's going to happen and act based on that. So for example, the inflation is pretty low right now (below 2% still), but the Federal Reserve is thinking about taking action because they're afraid that it might go over that target soon.