The key to understanding the recurrent crises of capitalism is the term ‘overproduction’.
Capitalism produces not to meet human needs first & foremost, but to make a profit. It produces commodities to sell for more money than initially spent purchasing the required inputs. Money, at its core, is nothing more than that special commodity that acts as the universal equivalent. In otherwords, one particular commodity becomes the measure of value of all other commodities. Gold & silver have traditionally played the role of commodity money. There isn’t just commodity money though; there’s also token money & credit money. Today’s notes & coins are token money, as are Bitcoins, & credit cards are the most obvious form of credit money. But to have a firm grasp on the nature of commodity production, let’s leave token & credit money to one side for the moment.