A mobile telephone or cellular telephone (commonly "mobile phone" or "cell phone") is a long-range, portable electronic device used for mobile communication. In addition to the standard voice function of a telephone, current mobile phones can support many additional services such as SMS for text messaging, email, packet switching for access to the Internet, and MMS for sending and receiving photos and video. Most current mobile phones connect to a cellular network of base stations (cell sites), which is in turn interconnected to the public switched telephone network (PSTN) (the exception is satellite phones).

There is one U.S. patent, Patent Number 887357 for a wireless telephone, issued 1908 to Nathan B. Stubblefield of Murray, Kentucky. He applied this to "cave radio" telephones and not directly to cellular telephony as we know it today. However, the introduction of cells for mobile phone base stations, invented in 1947 by Bell Labs engineers at AT&T, was further developed by Bell Labs during the 1960s. Radiophones have a long and varied history going back to Reginald Fessenden's invention and shore-to-ship demonstration of radio telephony, through the Second World War with military use of radio telephony links and civil services in the 1950s, while hand-held cellular radio devices have been available since 1983. Due to their low establishment costs and rapid deployment, mobile phone networks have since spread rapidly throughout the world, outstripping the growth of fixed telephony.

In 1945, the zero generation (0G) of mobile telephones was introduced. 0G mobile telephones, such as Mobile Telephone Service, were not officially categorized as mobile phones, since they did not support the automatic change of channel frequency during calls, which allows the user to move from one cell (the base station coverage area) to another cell, a feature called "handover".

In 1984, Bell Labs invented such a "call handoff" feature, which allowed mobile-phone users to travel through several cells during the same conversation. Motorola is widely considered to be the inventor of the first practical mobile phone for handheld use in a non-vehicle setting. Using a modern, if somewhat heavy portable handset, Motorola manager Martin Cooper made the first call on a handheld mobile phone on April 3, 1973.

The first commercial cellular network was launched in Japan by NTT in 1979. Fully automatic cellular networks were first introduced in the early to mid 1980s (the 1G generation) with the Nordic Mobile Telephone (NMT) system in 1981. This was followed by a boom in mobile telephone usage, particularly in Northern Europe.