When cartoonist Chester Gould gave comic strip detective Dick Tracy a two-way wrist radio, he couldn't have known that he was foreseeing the development of a variety of portable communications devices. The digital revolution of the late 20th century led to communications devices that make Tracy's wrist radio seem quaint.
In 1979, the world's first cellular telephone network went on line in Tokyo, Japan. Similar networks spread rapidly after that, and by 2006, the majority of people in North America, Europe and affluent areas of Africa, Asia and Latin America had access to cell phones. Reportedly, 206 million people use cell phones in the United States, as of 2011.
A smartphone is small computer that also functions as a telephone. Although features vary by manufacturer and model, smartphones typically include digital voice service, Internet access, email and text messaging. Other options include MP3 players, digital cameras and video players. Smartphones also run a wide range of computer applications for business and entertainment. Leading brands of smartphones include BlackBerry, iPhone, Motorola and Samsung.
A laptop is a mobile computer. When they were first introduced, they were little better than glorified calculators. Today's high-end machines have the same functionality as desktop computers, including Internet access that permits the use of various communications tools such as instant messaging, email and video conferencing. Popular models are manufactured by Dell, Apple, Gateway and Toshiba.
Personal Digital Assistant
Personal digital assistants, or PDAs, have evolved considerably since their introduction in 1993. Originally little more than electronic address books, PDAs are now multifunction portable computers. Functions vary but often include phone service, fax service, email and Internet connections. Users control their PDAs by writing information on touch-sensitive, liquid-crystal display, or LCD, screens with pen-like devices called a styluses. Employers often equip employees with PDAs in situations where laptop computers would be unfeasible.