There are two primary types of debt: secured and unsecured. The easiest way to understand whether or not you have secured or unsecured debt is to determine whether or not a creditor can take away an object or your property in the event that you suddenly become unable to make payments on the account.
If a creditor can take away tangible property or another item that is somehow attached to the debt, then that is a secured debt. If nothing can be taken from you if you stop making your payments, then that is considered an unsecured debt.
Unsecured debts are usually credit cards, unless you happen to get one of the handful of secured cards available on the market. A secured credit card can be a prepaid card (secured by the amount of your actual deposit), or a card that is secured by some other property or object. Medical bills are also considered an unsecured debt- as you did not have to put up an item as collateral in order to obtain the debt.
Secured debts are commonly large ticket items like mortgages and cars. If you fail to keep up with your mortgage payments, then the bank or mortgage lender can take your home as payment. If you dont keep up with your car...