Computers are a prime example of a digital device in everyday use. According to the Brooklyn College Department of Computer and Information Science, a digital device is one that converts information into numbers to allow for storage and transport of that information.
Digital devices have been in existence for well over 100 years, with the first digital device in widespread use being the telegraph. The telegraph was used to translate text into a series of dots and dashes, which were transferable along a line from one telegraph to another to allow for long-distance communications.
The telephone later replaced the telegraph as a widely used digital device, though earlier telephone systems also had an analog component that was used to transfer the voice portion of the call. The digital portion of earlier telephones was used to convey telephone number data, routing two or more phones to establish connections between them without the need for manual help from operators. Recent phone systems are entirely digital, however, with the audio converted into data for transfer along the phone line, where it is converted back into audio at the other end.
Modems are another recent example of a digital device, serving the same purposes as the old telegraph lines in converting analog information such as text, audio and video into digital signals for transmission along a networking cable.