Advantages
Purchase Power and Ease of Purchase - Credit cards can make it easier to buy things. If you don't like to carry large amounts of cash with you or if a company doesn't accept cash purchases (for example most airlines, hotels, and car rental agencies), putting purchases on a credit card can make buying things easier.
Protection of Purchases - Credit cards may also offer you additional protection if something you have bought is lost, damaged, or stolen. Both your credit card statement (and the credit card company) can vouch for the fact that you have made a purchase if the original receipt is lost or stolen. In addition, some credit card companies offer insurance on large purchases.
Building a Credit Line - Having a good credit history is often important, not only when applying for credit cards, but also when applying for things such as loans, rental applications, or even some jobs. Having a credit card and using it wisely (making payments on time and in full each month) will help you build a good credit history.
Emergencies - Credit cards can also be useful in times of emergency. While you should avoid spending outside your budget (or money you don't have!), sometimes emergencies (such as your car breaking down or flood or fire) may lead to a large purchase (like the need for a rental car or a motel room for several nights.)
Credit Card Benefits - In addition to the benefits listed above, some credit cards offer additional benefits, such as discounts from particular stores or companies, bonuses such as free airline miles or travel discounts, and special insurances (like travel or life insurance.) While most of these benefits are meant to encourage you to charge more money on your credit card (remember, credit card companies start making their money when you can't afford to pay off your charges!) the benefits are real and can be helpful as long as you remember your spending limits.