What did credit have to do with great depression?

Credit is essentialy a loan given that is paid back with interest. Arguably, credit caused the Great Depression. Many Americans invested in the stock market with credit when they did not have the money, so when a recession in the stock market occurred, many stockholders were in huge debt. Banks that lended money were out of money, and depositors lost money. This caused homes to foreclose, and because of the decrease in consumer purchasing power (people were in debt), companies laid off workers and unemployment rose.