For some people, cell phones are a wonderful convenience of modern life; for others, they are irritating contraptions that should be banned from public areas. A mobile phone or cell phone is an electronic telecommunication device with the same basic capability as a conventional fixed-line telephone, but which is also entirely portable and is not required to be connected with a wire to the telephone network. Most current mobile phones connect instead to the network using a wireless radio wave transmission technology. The mobile phone communicates via a cellular network of base stations, also known as cell sites, which are in turn linked to the conventional telephone networks. In addition to the standard voice function of a telephone, a mobile phone can support many additional services such as SMS for text messaging, packet switching for access to the Internet, and MMS for sending and receiving photos and videos. In less than twenty years, mobile phones have gone from being rare and expensive pieces of equipment used by businesses to an all pervasive low-cost personal item. In many countries, mobile phones now outnumber land-line telephones, with most adults and many children now owning mobile phones. It is not uncommon for young adults to simply own a mobile phone instead of a land-line for their residence. In some developing countries, where there is little existing fixed-line infrastructure, the mobile phone has become widespread.
With high levels of mobile telephone penetration, a mobile culture has evolved, where the phone becomes a key social tool, and people rely on their mobile phone address book to keep in touch with their friends. Many people keep in touch using SMS, and a whole culture of "texting" has developed from this. The commercial market in SMSs is growing. Many phones even offer Instant Messenger services to increase the simplicity and ease of