This is getting heavy – but what even is money?

There are a few things in life that we don’t like to think about, because if we do, something mundane can become so complex that we give ourselves a headache.
Who closes the bus door once the driver gets off? How did the alphabet get put in alphabetical order? Why is there a ‘d’ in fridge, but not in refrigerator? And perhaps the most perplexing of all: What even is money?