Article: The Internet has led to a huge increase in credit-card  fraud.Your card information can even be on sale on an illegal website.Websites offering cheap goods and services should be regarded with care.Online shoppers who enter their credit-card information may never receive the goods they thought they had bought. The thieves then go shopping with your card number--or sell the information over the Internet.Computer hackers have broken down security system, raising questions about the safety of card holder information. Several months ago, 25,000 customers of a CD universe, an online music retailer , were not lucky.Their names, addresses and credit-card numbers were posted on a Website after the retailer refused to pay $ 157,828 to get back the information.Credit-card firms are now fighting against online fraud.Master-card is working on plans for web-only credit-cards, with a lower credit limit.The card can be used only for shopping online.However, there are a few simple steps you can take to keep from being cheated. Ask about your credit-card firm's online rules: under British law, card holders are responsible for the first $ 78 of any fraudulent spending.And shop only at secure sites: send your credit-card information only if the website offers advanced security system.If the security is in place, a letter will appear in the bottom right-hand corner of your screen.The website address may also start with https://--the extra "s" stands for security.If in doubt, give your credit-card information over the telephone. Keep your password safe: most online sites require a user name and password before placing an order.Treat your password with care. 
 Answer: fraud on the Internet happens very often
According to this passage most people worry about shopping on the Internet because   _  .