Question

What is the main idea of this paragraph? Identity thieves may steal your information from a letter in your mailbox, from transactions on the Internet, or even from a credit card receipt that you accidentally left at a restaurant or store. In the past, many of these receipts contained your credit card number—right there for anyone to see and use. If you signed the receipt, anyone who found it also had a copy of your signature. Using this information, a thief could easily purchase merchandise either by phone or on the Internet. Today, most receipts show only the last four numbers of the credit c