Believe it or not, cell phones have been around for over a quarter of a century.The first commercial cell phone system was developed by the Japanese in 1979. But cell phones have changed a lot since that time. The early cell phones appeared big and heavy but they have developed into small and light palm­sized models. There have been huge developments in their functions，too. We have had call forwarding, text messaging, answering services and hands­free use for years, but now the manufacturers equip countless new facilities, such as instant access to the Internet and receiving and Sending photos. Cell phones have become very common in our lives；recent statistics suggest as many as one in three people on the planet now has a cell phone, and most of them say they couldn't live without one. Cell phones are used in every area of our lives and have become a necessary tool, used for essential arrangements, social contact and business. They have made it easier to call for help on the highway. They have made it possible to keep in touch with people “on the move” when people are traveling. Cell phones have made communication easier and have reduced the need for family arguments. We can use cell phones to let our family know we'll be late or if there's a change of plan or an emergency. Cell phones have eased the worries of millions of parents when their teenagers are out late, and they can now contact their children at any time. This does not mean that cell phones are all good news. They have brought with them a number of new headaches for their owners: it costs a lot to replace stolen phones, something that is becoming a frequent occurrence, and have you ever seen such huge phone bills? More serious, however, is the potential health problem they bring: there are fears that radiation from the phones may cause brain tumor(肿瘤). This may be a time bomb waiting to happen to younger people who have grown up with cell phones that they simply can't live without.