If your card offers a grace period, avoid paying interest on purchases by paying your account in full each month. (complexsearch.com)
For example, you might not have to pay interest on purchases for the first nine months when you open a new credit card. (sapling.com)
You will be charged interest on the purchases for the billing cycle, which is the case whenever you carry a balance — meaning you fail to pay the full amount owed. (valuepenguin.com)