The word digital began with fingers and an anti-aircraft gun
Digital shares its root with digit and the Latin digitus, finger, because people counted on their hands. Its modern sense arrived in 1942, when George Stibitz of Bell Telephone Laboratories used it for the rapid electrical pulses of a device built to aim and fire anti-aircraft guns.
Digital data is information written as a string of separate symbols, each drawn from a limited set, such as letters or numerals. A text file is a simple example. Most modern systems use binary, where every symbol, or bit, is either 0 or 1. Analog data, by contrast, takes values from a continuous range and can shift smoothly over time, like the changing air pressure in a sound wave. Since about 1960 all data inside computers has been digital, and it now feeds data science, where statistics and machine learning hunt for patterns.
Turning symbols into data is easier than digitising sound or pictures, because no sampling is needed. A keyboard is a grid of switches at the crossings of horizontal and vertical lines. A small processor scans the grid, powering each line in turn to see which keys connect, then reports a scan code to the main processor through an interrupt. Press two keys, or press, release and press again, within one scanning interval and the input is lost. Devices with few buttons, such as joysticks, can pack each button's state into the bits of one word, handy for combinations like shift and control.
Security specialists describe digital data in three states: at rest in storage, in transit across networks, and in use in memory. Data at rest, from archives and backup tapes to phones and cloud drives, faces both hackers and physical theft, and the longer it sits unused, the likelier outsiders are to reach it. Common defences include passwords and strong encryption such as AES or RSA, with keys stored apart from the data and changed regularly.
Tokenisation takes another route, swapping sensitive values for meaningless stand-ins of the same type and length, so older systems keep working. Storage location matters too: data held on American soil can be demanded under the USA PATRIOT Act, even if it belongs to European citizens.
Source: Digital data
