The Internet has led to a huge increase in credit-card (信用卡) fraud. Your card information could even be for sale in an illegal Web site (网站). Web sites offering cheap goods and services should be regarded with care. On-line shoppers who enter their credit-card information may never receive the goods they thought they bought. The thieves then go shopping with your card number or sell the information over the Internet. Computers hackers (黑客) have broken down security (安全) systems , raising questions about the safety of cardholder information. Several months ago, 25, 000 customers of CD Universe, an on-line music retailer (批发商) , were not lucky. Their names, addresses and credit-card numbers were posted on a Web site after the retailer refused to pay US $ 157, 828 to get back the information. Credit-card firms are now fighting against on-line fraud. Mastercard is working on plans for web—only credit-card, with a lower credit limit. The card could be used only for shopping on-line. However, there are a few simple steps you can take to keep from being cheated. Ask about your credit-card firm's on-line rules Under British law, cardholders are responsible (对……负有责任的)for the first US $ 78 of any fraudulent spending. And shop only at secure sites: Send your credit-card information only if the web site offers advanced secure system. If the security is in place, a letter will appear in the bottom right-hand corner of your screen. The Web site address may also start with https://—the extra's' stands for secure. If in doubt, give your credit-card information over the telephone. Keep your password safe. Most on-line sites require a user name and password before placing an order. Treat your passwords with care. What do most people worry about the Internet according to this passage?