A finance charge is the total cost of credit including interest and other fees that a credit company may charge if you carry a balance on your credit card. It is dangerous to only pay the minimum amount each month because you will accumulate interest and have a bad credit report over time. The major credit card companies are MasterCard, Visa, American Express, and Discover. A credit rating refers to a person's history of paying bills on time, with 800 being a good rating and 300 being a bad rating.