A smartwatch is a portable wearable computer that resembles a wristwatch. Most modern smartwatches are operated via a touchscreen, and rely on mobile apps that run on a connected device (such as a smartphone) in order to provide core functions.

Early smartwatches were capable of performing basic functions like calculating, displaying digital time, translating text, and playing games. More recent models often offer features comparable to smartphones, including apps, a mobile operating system, Bluetooth and Wi-Fi connectivity, and the ability to function as portable media players or FM radios. Some high-end models have cellular capabilities, allowing users to make and receive phone calls.

While internal hardware varies, most smartwatches have a backlit LCD or OLED electronic visual display and are powered by a rechargeable lithium-ion battery. They may also incorporate GPS receivers, digital cameras, and microSD card readers, as well as various internal and environmental sensors such as thermometers, accelerometers, altimeters, barometers, gyroscopes, and ambient light sensors. Some smartwatches also function as activity trackers and include body sensors such as pedometers, heart rate monitors, galvanic skin response sensors, and ECG sensors. Software may include maps, health and exercise-related apps, calendars, and various watch faces.

The first digital watch was the Pulsar, introduced by the Hamilton Watch Company in 1972. The "Pulsar" became a brand name, and would later be acquired by Seiko in 1978. In 1982, a Pulsar watch (NL C01) was released which could store 24 digits, likely making it the first watch with user-programmable memory, or the first "memorybank" watch.

With the introduction of personal computers in the 1980s, Seiko began to develop computers in the form of watches. The Data 2000 watch, named for its ability to store 2000 characters, came with an external keyboard for data entry. Data was synchronised from the keyboard to the watch via electromagnetic coupling (wireless docking). Its memory was small, at only 112 digits. It was released in 1984, in gold, silver, and black.

These models were followed by many others from Seiko during the 1980s, most notably the "RC Series". The RC-1000 Wrist Terminal from Seiko Epson was released in 1984; it was the first Seiko model to interface with a computer and was priced at around £100. It featured 2 KB of storage, a two-line, 12-character display, and data transfer with a computer via an RS232C interface. It was powered by a computer on a chip, and was compatible with most of the popular PCs of that time, including Apple II, II+ and IIe, BBC Micro, Commodore 64, IBM PC, NEC 8201, Tandy Color Computer, Model 1000, 1200, 2000 and TRS-80 Model I, III, 4 and 4p. The RC-20 Wrist Computer was released in 1985, followed by the RC-4000 and RC-4500.

During the 1980s, Casio began to market a successful line of "computer watches" in addition to its calculator watches, most notably the Casio data bank series. Casio and other companies also produced novelty "game watches", such as the Nelsonic game watches.

Although pager watches were predicted in the early 1980s, it took until the end of the decade for them to become more common. Two models were particularly notable: Motorola and Timex produced the Wrist Watch Pager, while AT&T Corporation and Seiko produced the MessageWatch.