
So there’s two types of cards that people use: Debit cards and Credit cards. Debit cards are usually tied to a bank account of some kind and works exactly like you’re thinking “I put money in and I can spend that money but no more than that” Credit cards are card that you can use to borrow money for a short time before paying back what you borrowed (with some interest if not paid off monthly). The point of them is to borrow money now and pay it back when you have the funds
The cash you put down is a refundable deposit that basically just sets your credit limit. Ei $500 deposit=$500 credit limit per month. You then pay back whatever you spend at the end of each month. When your balance is paid off and you close the account you get the $500 back (or some banks will graduate you to an unsecured traditional credit card and refund the deposit automatically)
Say you trip and sprain your ankle and the bill to get you checked out is $500 but you only have $250 in your checking account (VERY made up numbers but it’s the principle). You can use your credit card to pay off that bill that you just could not afford. So then at the end of the month you’ll get a statement saying what you owe and a minimum payment amount. As long as you pay that minimum amount every single month you won’t be in trouble
Anything not paid off at the end of the month gains some interest and will cost a little more the next month. Say your minimum payment was $50, your bill would then be $450 + the interest on that $450 for the month, but as long as you make sure you are paying MORE than that interest you will eventually pay it off; paying more and earlier helps out a LOT with paying it off, even just an extra $20.
But yeah credit cards are meant for big but small purchases that are hard to budget for (think buying stoves or fridges, not buying a car on credit cards). They’re meant to be a short term assistance but if you aren’t careful with how you spend it can snowball into insane debt (interest on interest on interest…). But if you pay it off regularly and don’t use more than like 30% of your limit, you show to banks that you are responsible with debt and will help with buying car and house loans later