There are almost as many different rewards programs are there are credit cards. Common benefits offered include:

Air Travel Miles

Many credit cards partner with specific airlines and offer more generous air travel miles if you fly with them. There are many airlines cards to choose from, such as the American Express Gold Delta SkyMiles card or the Hawaiian Airlines World Elite MasterCard. Some credit cards, such as Barclaycard Arrival Plus World Elite MasterCard, allow consumers to earn miles that can be applied against any travel-related purchase: food, gas, lodging or car rentals. Some of these cards offer more points during introductory periods or to those using self-serve online tools to apply points to purchases.

Cash Back on Purchases and Payments

Different cards offer different amounts of cash back for purchases or payments. The Blue Cash Preferred Card from American Express offers 6% back on groceries up to $6,000 dollars each year and an unlimited 3% cash back on gas and department store purchases. The Citi Double Cash Card offers 1% cash back when purchases are charged to the card and an additional 1% cash back when those purchases are paid off.

Introductory Rate Period: Purchases and Transfers

Many credit cards offer a low introductory interest rate, often 0%. Cards vary as to whether they charge a different rate on balance transfers and whether balance transfers are covered by introductory rates. The Discover It card has a 14-month introductory rate of 0% on balance transfers and purchases.

Discounts or Gift Cards

The Visa Card from Chase offers a promotion that gives a $50 Amazon gift card upon being accepted to the program, 3% cash back on purchases, 2% on purchases at gas stations, restaurants and drug stores, and 1% on other purchases. The My Best Buy credit card offers 5% back on Best Buy purchases and 10% back on purchases made on the day the card is applied for.

Insurance on Rental Cars and Card Balances

Many, but not all, credit cards offer insurance on rented cars if that card is used to book the rental. It is also necessary to waive the insurance offered by the rental car company. There are some cards, even offered in the same network, that offer varying levels of insurance. It is always advisable to call an individual company and make sure that the card offers insurance before renting a car. (For related reading, see "Debit or Credit Card: Which to Use for Car Rentals.")

Many credit cards offer other insurance that makes payments on behalf of the cardholder in the event he or she is unable to make payments because of loss of income. There have been judicial actions by the Consumer Financial Protection Bureau (CFPB) for unethical practices in the sales and distribution of these insurance policies, including multimillion-dollar fines levied against Discover and Capital One.

(For related reading, see "How to Make Credit Card Rewards Worth It.")