Say you owe $1,000 on a credit card. This month, the card adds $20 interest, the cost of borrowing. You pay $25, the minimum allowed. No new charges.
Now you owe $995. Only $5 cut the debt. The other $20 paid the interest.
Next month, interest is added again. U.S. card bills show how long paying just the minimum would take. It can take years.