What is a responsible use of credit?

Buying something on credit and making many payments on the account over months gradually paying down the debt. If you are seeking to build credit, then don't pay it all off too quickly as that doesn't establish a history of making payments. It takes at least 6 months of payments to even affect your credit report. Also, don't only pay minumim payments. You want to establish that you can be trusted and will not strecth yourself too thin.