Convenience
There are very few places that don’t take a credit card, so instead of carrying a cash with you everywhere, you can just bring a credit card.  Also you won’t be “forced” to carry change that you receive  after paying for something in cash.

Rewards
Many credit cards offers you incentives based on the amount you spend with your credit card.  Rewards vary from cash back to points that you can redeem for awards.

Security
If your credit card is stolen, you are only legally obligated to pay a maximum of $50 of the fraudulent charges but most companies will even waive this.

Track your Spending
By using your credit card, you’ll have a record of everything that you spent on your monthly credit card statement.

Credit Card Protection from Merchants
If you have a dispute with a merchant your credit card company can do a charge back and issue you a credit if they rule in your favor

Build Credit
Using a credit card will help you in building a better credit score (if you pay your bills on time).

Insurance/Purchase Protection
Depending on your credit card, they may offer purchase protection or travelers insurance.