Glossary
Plain-language definitions of terms used in the articles, each linked to the articles where the idea matters.
Terms
Amplifier
A device that increases the strength of an electrical signal. Vacuum tubes and later transistors made practical amplifiers possible for radio, telephony, and sound recording.
Analog
A way of representing information with a continuously varying quantity, such as the wiggles in a record groove or the voltage of a radio signal, rather than with discrete numbers.
Aqueduct
A channel or bridge-like structure built to carry water from a source to a city or field, usually relying on a gentle, steady slope.
ARPANET
An experimental computer network funded by a United States defense research agency, first linked in 1969. It was one of the main precursors of the modern Internet.
Assembly line
A production arrangement in which the product moves past fixed workstations, each performing a limited task. The moving version became famous through automobile manufacturing in the early twentieth century.
Astrolabe
A portable instrument used to measure the height of stars and the Sun above the horizon, helpful for telling time and finding latitude. It was refined over centuries, notably in the medieval Islamic world.
Automaton
A self-operating mechanical device that follows a fixed sequence of actions, often built for entertainment or demonstration long before modern robots.
Blast furnace
A tall furnace in which air is forced through burning fuel and iron ore to produce molten iron. It allowed iron to be made on a far larger scale than small bloomery furnaces.
Boiler
A closed vessel in which water is heated to produce steam under pressure, the source of power in steam engines.
Bronze
An alloy of copper, usually with tin, that is harder than pure copper and easier to cast. It gave its name to an era of toolmaking.
Cathode-ray tube
A vacuum tube in which a beam of electrons is steered onto a phosphor-coated screen to form an image. It was the heart of most televisions and monitors for decades.
Cellular network
A mobile-phone system that divides coverage into small areas, or cells, each served by its own transmitter, allowing the same radio frequencies to be reused across a region.
Central telephone exchange
A facility where telephone lines are connected to one another on demand, first by human operators and later by automatic switching equipment.
Chronometer
A highly accurate, portable timekeeper designed to keep reliable time at sea, making it possible to determine longitude by comparing local time with a reference time.
Circuit board
A flat board that holds electronic components and connects them with conductive paths, so that complex circuits can be manufactured repeatably.
Compass
An instrument with a magnetized needle that aligns with the Earth's magnetic field, giving a constant reference for direction.
Compiler
A program that translates instructions written in a programming language into the machine code a computer can execute.
Cuneiform
A writing system made by pressing a wedge-shaped stylus into wet clay, used in Mesopotamia for thousands of years to write several languages.
Cybernetics
A field, named in the 1940s, that studies control and communication in machines and living things, with an emphasis on feedback.
Daguerreotype
An early photographic process, announced in 1839, that produced a unique, highly detailed image on a silver-coated metal plate.
Digital
A way of representing information as discrete values, usually numbers written in binary. Digital signals can be copied and processed without gradual degradation.
Domestication
The long process by which people selected and cared for plants and animals until they became dependent on human management and differed from their wild relatives.
Dynamo
An early electrical generator that converts mechanical rotation into direct electric current using electromagnetic induction.
Electromagnetic induction
The production of an electric current in a conductor by a changing magnetic field, the principle behind generators, transformers, and many motors.
Emulsion
A light-sensitive coating, typically silver salts in gelatin, that records an image on film or plates when exposed to light and then chemically processed.
Feedback
The use of a system's own output to adjust its operation, as in a governor that limits the speed of an engine or a robot that corrects its position.
Hypertext
Text that contains links to other text, allowing readers to move between related documents in a non-linear way.
Incunabulum
A book printed in Europe before 1501, in the earliest decades of printing with movable type.
Integrated circuit
An electronic circuit whose components and connections are fabricated together on a single piece of semiconductor, commonly called a chip.
Interchangeable parts
Components made to tolerances tight enough that any one can replace another of the same kind, simplifying assembly and repair.
Internet
A global system of interconnected computer networks that exchange data using shared protocols. It is distinct from the Web, which is one service that runs on it.
Jacquard loom
A weaving loom controlled by punched cards that determine the pattern, introduced in the early nineteenth century and an influence on later data-processing ideas.
Kinetoscope
A cabinet device developed in the 1890s in which one viewer at a time watched a short film loop through a peephole.
Machine learning
A family of methods in which computer systems improve at a task by finding patterns in data rather than by following only hand-written rules.
Machine tool
A power-driven machine, such as a lathe or milling machine, used to shape metal and other materials with precision.
Microprocessor
A central processing unit contained on a single integrated circuit, which made small, inexpensive computers practical.
Modulation
Varying a property of a carrier wave, such as its amplitude (AM) or frequency (FM), so that it carries a signal such as speech or music.
Moore's law
An observation, first made in the 1960s and later revised, that the number of components on an integrated circuit tended to double at regular intervals. It is an industry trend, not a law of physics.
Movable type
Individual, reusable pieces carrying a single letter or character, assembled into lines and pages for printing and then taken apart again.
Neural network
A computing model built from many simple interconnected units whose connection strengths are adjusted, often through training on examples.
Oldowan
The name given to the oldest widely accepted tradition of stone tools, consisting of simple flakes and cores first identified at Olduvai Gorge in Tanzania.
Packet switching
A method of sending data in small, individually addressed packets that may take different routes through a network and are reassembled at the destination.
Papyrus
A writing material made from pressed strips of a Nile-valley reed, widely used in the ancient Mediterranean before parchment and paper.
Parchment
A writing surface made from animal skin that has been scraped, stretched, and dried, more durable than papyrus and common in medieval manuscripts.
Patent
A legal grant of exclusive rights to an invention for a limited time, in exchange for public disclosure. A patent records a claim and a date; it does not by itself prove who invented something first.
Programming language
A formal notation for writing instructions that a computer can carry out, ranging from close-to-the-hardware assembly to high-level languages.
Protocol
An agreed set of rules for how devices exchange information, such as how data is formatted, addressed, and acknowledged.
Punched card
A stiff card with holes in set positions that represent data or instructions, used in looms and then in tabulating and early computing machines.
Robot
A machine that can carry out physical tasks under programmed or sensor-driven control. The word comes from a 1920 Czech play and was first applied to fictional artificial workers.
Semiconductor
A material, such as silicon, whose ability to conduct electricity can be controlled, which makes it the basis of transistors and integrated circuits.
Sextant
A hand-held instrument that measures the angle between a celestial body and the horizon using mirrors, widely used for navigation at sea from the eighteenth century.
Sociotechnical system
A view of technology as a combination of machines, people, institutions, rules, and practices that depend on one another, rather than as devices alone.
Stored-program computer
A computer that keeps its instructions in memory alongside its data, so it can be reprogrammed without rewiring.
Taylorism
A management approach from the early twentieth century that broke work into measured steps to raise output. It shaped factory organization and drew criticism from workers.
TCP/IP
The pair of protocols, Transmission Control Protocol and Internet Protocol, that define how data is addressed, sent, and reassembled across the Internet.
Transistor
A small semiconductor device that can amplify or switch electrical signals. It replaced vacuum tubes in most electronics from the 1950s onward.
Turing test
A proposal by Alan Turing in 1950 to judge whether a machine can imitate human conversation well enough that an interrogator cannot reliably tell it apart from a person.
Vacuum tube
A glass or metal tube with electrodes in a vacuum that can amplify or switch signals. It powered radio, television, and early computers before transistors.
Web browser
A program that retrieves documents from servers on the Web and displays them, following links between pages.
Woodblock printing
A printing method in which a whole page is carved in relief into a block of wood, inked, and pressed onto paper or cloth.